This is a guide to some of the technical or obscure terms related to the hobby of infiltration. We don't use code language or jargon to exclude anyone, but because it's a specialized hobby we've had to adopt or invent some specialized terms. Thanks to FiL for much of the draining vocabulary. If you'd like to contribute some words, please do.

abseil <German> v. rappel; see rappel
back breaker adj. long, low tunnel in a drain
ball buster adj. round concrete pipe drain with wide section of water
BASE jump v. leap from bridges, aerials (antennae), structures (skyscrapers, landmarks) or earth (cliffs); not really infiltrating, but some infiltrators feel solidarity with base jumpers
buildering n.,v. climbing buildings, with or without tools and support devices
bunker n. underground military command post, as found throughout Australia and Europe, particularly in Britain
burn v. ruin for others through lack of subtlety (i.e. "some guys burned the new tunnels by tagging everywhere, now they're kept locked")
cacophony society n. a group whose members pursue "experiences beyond the pale of mainstream society through subversion, pranks, art, fringe explorations and meaningless madness" and who share some ideals with urban explorers
catacomb n. subterranean burial grounds and the mazes of tunnels connected to them, as found in several older European cities, including Paris and Rome (strictly speaking, the term "catacomb" only applies to the burial grounds)
cataphiles n. those who explore catacombs
catch basin n. tank located under the street where water collects before flowing into drains
Cave Clan n. group that explores manmade tunnels and structures, mainly drains; originally based in Melbourne but now found in most capital cities of Australia
central utilities building or CUB n. on a college or university campus, the building that supplies the rest of the campus with electricity, heat, cool air and water, usually via steam tunnels
chamber n. huge, long room in a drain
chatière <French> n. ventilation hole (or "squeeze hole") used to enter catacombs
chimney v. to climb by using various body parts to provide force on opposing walls
Clannies n. annual award night/party held by the Melbourne Cave Clan at the conclusion of the draining season
closed circuit television or CCTV n. television signals transported directly from a camera to a monitor via wires, without broadcasting
college tunnel n. see steam tunnel
combined sewage overflow or CSO n. in older drainage systems, storm sewers and sanitary sewers may be connected to some degree, resulting in this unfortunate occurrence during serious storms
crater <climbing jargon> v. to fall from a height and hit the ground (as in, "I almost cratered!")
credibility prop n. an item such as a clipboard or briefcase, carried or used by an infiltrator to reduce suspicion
creeper n. one who infiltrates
cut-and-cover adj. subway tunnels created by a process of digging down from the top and covering up the hole, as opposed to boring a tube
darkie n. see stormwater drain
digestive <from Senor Jojo> adj. a full-length expedition that goes in one end and out the other
diggers n. group of underground explorers in Russia
drain v. explore stormwater drains (see stormwater drain)
drop n. a small waterfall in a drain
expo <from expedition> n. a mission attempted by a group of people
flashlight n. American/Canadian word for torch
freighthop v. catch free rides aboard freight trains (some dispute that this is really infiltrating)
grilles n. metal bars found in the roof or sides of a drain; rooms made entirely of grilles are called grille rooms
gutter box n. small space or room underneath the slit in a gutter through which the water drains
HEPA filter n. high efficiency particulate air filters, useful in keeping asbestos fibres out of one's respiratory system
Il Draino n. magazine of the Cave Clan, comes out approximately every three months
infiltration n.,v. going places you're not supposed to go in general; covers urban exploration as well as simply dropping in to conventions uninvited and the like
Infiltration n. zine about going places you're not supposed to go, comes out about five times a year
junction n. point where two sections of a drain meet; a junction room is a room where two tunnels join into one
labyrinth n. a series of connected tunnel systems built for different purposes
Lift-o-Matic n. simple manhole key produced by the Cave Clan
loop n. two distinct drain tunnels separating but rejoining further upstream or downstream
maglite n. favoured brand of flashlight/torch
manhole n. name for either a hole in the street leading underground or the underground room itself; sometimes used as shorthand "manhole cover"
metro n. the name for the subway system in both Paris and Montreal
mole people n. the hundreds or thousands of people who live in the tunnels under New York City, according to a book of the same name by Jennifer Toth
mummy n. tunnel shape so named because it resembles a mummy's sarcophagus (referred to by the water board as a horseshoe)
overflow n. a drain separate from the main tunnel built to carry excess water when the water level in the main tunnel is high; normally dry
physical plant n. at a college or university campus, the department which is responsible for maintaining the central utilities building and the steam tunnels; sometimes also used as a synonym for central utilities building
popper n. device used to open a manhole cover; the Lift-o-Matic is one kind
ramp n. in a drain, a slope not steep enough to be a slide
rappel v. descend a wall or steep face using a doubled rope
rebar n. steel reinforcing rod in used in concrete
RCP n. round concrete pipe (usually used in reference to the drain shape)
RT adj.,n. rapid transit, sometimes used as a short form for "train that runs on a rapid transit system"
sanitary sewer n. a sewer that isn't sanitary -- that is, the kind drainers avoid
sewering n.,v. see draining
shaft n. vertical passage connected to a tunnel
shrinker n. drain that just continues to get smaller as you head upstream without exiting
slide n. steep section of a drain, steeper than a ramp
skunneling n. the activity of skateboarding in tunnels (usually drains)
social engineering <from hacker jargon> n.,v. dealing with people (employees, security guards) in a manner that allows you to get past them or obtain information from them
spelunking <from caver jargon> n.,v. exploring caves, whether natural or manmade; most (natural) cavers prefer to think of themselves as speleogists rather than spelunkers
split n. part where a drain divides
steam tunnel n. underground passages that house pipes carrying steam and other utilities; found under large colleges, universities and other large institutions
step irons n. metal rungs set into a wall to provide a ladder
storm sewer n. see stormwater drain
stormwater drain n. underground tunnel that shuttles rain or melted snow from urban areas back out to the wilds of nature where it belongs
stunneling <student or steam tunneling> n.,v. travelling through steam tunnels under colleges or universities
tag (up) v. write graffiti consisting of nothing more creative than an explorer's name
texta n. big, thick marker used for graffiti
third rail n. the electrified rail that powers most subway systems; to be avoided
tomb n. synonym for drain used when drain is named after someone, from a Melbourne tradition of members naming drains after themselves (i.e. Sloth's Tomb, Bob's Tomb)
TonkaBoys n. construction worker
topside n. above ground
torch n. British/Australian word for flashlight
tract n. pamphlet circulated among cataphiles, often via the catacombs
tube n. subway tunnels created by a boring machine, or a nickname for the London Underground
Underground, the n. the oldest and one of the largest subway systems in the world, in London
urban adventure n. very much like urban exploration, but with the focus upon experiences rather than sight-seeing
urban exploration n. the investigation of manmade structures not designed for public consumption, from mechanical rooms to stormwater drains to rooftops; usually such areas are off-limits
vad <derived from the hacked command for the computer text game Adventure> v. explore - the word adopted by MIT students for real-world hacking
viewing hole n. an eye-level hole, usually rectangular, cut into the boards surrounding a construction site to appease curious passersby
water moccasin n. poisonous snake rumoured to inhabit drains in the southern USA
waterfall n. in a drain, a large drop over which the drain water falls
yabbies <from Australian> n. fresh water crustaceans found in Australian drains

The full, paper version of Infiltration can be ordered for $2 cash (US or Cnd) from Infiltration, PO Box 13, Station E, Toronto, Ontario, M6H 4E1, Canada. Please toss any comments, queries or contributions to Ninjalicious.