Definition of thingum in English:

thingum

(also thing'um, thingam, thingem)

noun

  • Informal= "thingummy". In early use (with reference to a person) also "Mr Thingum".

Origin

Mid 17th century (in an earlier sense). Apparently an extended form of thing, perhaps after Latin nouns in -um or (accusative forms in) -am.

Pronunciation

thingum

/ˈθɪŋəm/