Absence of loops.

A moth, Achaea janata, of the family Erebidae, having a caterpillar which arches part of its body into a loop in order to bring the back part of the body forward as it walks.

plural of semi-looper

(US, historical) A loophole in early-1900s American immigration law that allowed Chinese people to enter the country if they managed a Chinese restaurant, resulting in a greater-than-average increase of those establishments over several decades.

(rail transport) Alternative form of loop line

plural of loopline

(slang, idiomatic, humorous) The idea that a woman can engage in anal sex and still remain a virgin.

A little loop.

plural of looplet

Alternative form of every law has its loophole