(aviation) A manually positioned marker in flight instruments.
(broadcasting) A small, usually transparent or translucent image placed in a corner of a television program to identify the broadcasting network or cable channel.
(chiefly LGBT, "the bug") HIV.
(chiefly computing and engineering jargon) A problem that needs fixing.
(entomology) An insect of the order Hemiptera (the “true bugs”).
(gambling, slang) A metal clip attached to the underside of a table, etc. to hold hidden cards, as a form of cheating.
(gambling, slang) A small piece of metal used in a slot machine to block certain winning combinations.
(informal) A keen enthusiast or hobbyist.
(informal) An enthusiasm for something; an obsession.
(informal) Any insect, arachnid, or other terrestrial arthropod that is a pest.
(obsolete) Hobgoblin, scarecrow; anything that terrifies.
(paleontology, slang) A trilobite.
(petroleum industry, slang, dated) Synonym of oil bug.
(poker) A limited form of wild card in some variants of poker.
(printing) Synonym of union bug.
(slang, US, horse-racing) An asterisk denoting an apprentice jockey's weight allowance.
(slang, US, horse-racing, by extension) A young apprentice jockey.
A concealed electronic eavesdropping or intercept device.
A contagious illness, or a pathogen causing it.
A semi-automated telegraph key.
A small and usually invisible file (traditionally a single-pixel image) on a World Wide Web page, primarily used to track users.
Any of various species of marine or freshwater crustaceans; e.g. a Moreton Bay bug, mudbug.
verb
(informal, intransitive) To act suspiciously or irrationally, especially in a way that annoys others.
(informal, transitive) To annoy.
(transitive) To install an electronic listening device or devices in.
