Word Study
thingummy
OXFORD DICTIONARY
thingummy, n. (pl. -ies) (also thingamy, thingumabob, thingumajig) colloq. a person or thing whose name one has forgotten or does not know or does not wish to mention.
Etymology
THING + meaningless suffix
ROGET THESAURUS
thingummy
Neologism
N neology, neologism, newfangled expression, nonce expression, back-formation, caconym, barbarism, archaism, black letter, monkish Latin, corruption, missaying, malapropism, antiphrasis, pun, paranomasia, play upon words, word play, double- entendre, palindrome, paragram, anagram, clinch, abuse of language, abuse of terms, dialect, brogue, idiom, accent, patois, provincialism, regionalism, localism, broken English, lingua franca, Anglicism, Briticism, Gallicism, Scotticism, Hibernicism, Americanism, Gypsy lingo, Romany, pidgin, pidgin English, pigeon English, Volapuk, Chinook, Esperanto, Hindustani, kitchen Kaffir, dog Latin, macaronics, gibberish, confusion of tongues, Babel, babu English, chi-chi, figure of speech, byword, colloquialism, informal speech, informal language, substandard language, vernacular, vulgar language, obscene language, obscenity, vulgarity, jargon, technical terms, technicality, lingo, slang, cant, argot, St. Gile's Greek, thieves' Latin, peddler's French, flash tongue, Billingsgate, Wall Street slang, pseudology, pseudonym, Mr, So-and-so, wha d'ye call 'em, whatchacallim, what's his name, thingummy, thingumbob, je ne sais quoi, neologist, coiner of words, neologic, neological, archaic, obsolete, colloquial, Anglice.For further exploring for "thingummy" in Webster Dictionary Online