tertium quid

American  

[tur-shee-uhm kwid, ter-ti-oom kwid] / ˈtɜr ʃi əm ˈkwɪd, ˈtɛr tɪˌʊm ˈkwɪd /

noun

1. something related in some way to two things, but distinct from both; something intermediate between two things.

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tertium quid British  

/ ˈtɜːtɪəm ˈkwɪd /

noun

1. an unknown or indefinite thing related in some way to two known or definite things, but distinct from both

   there is either right or wrong, with no tertium quid

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Etymology

Origin of tertium quid

1715–25; < Latin, translation of Greek tríton·ti some third thing

Example Sentences

In this case, this blog is a tertium quid to my other two blogs—it’s related to them but something different altogether.

From Forbes • Jul. 9, 2012

Webb, the tertium quid, is more unlike Chesterton than seems possible.

From Time Magazine Archive

Ironists recalled that for many years Ferdinand and Marie were estranged by a tertium quid, Helene Vacarescu.

From Time Magazine Archive

And thus our several natures sweetly blent, We'd live and love together, until death Should decompose the fleshly tertium quid, Leaving our souls to all eternity Amalgamated.

From The Book of Humorous Verse by Wells, Carolyn

The word 'crank,' which became familiar at the time of Guiteau's trial, fulfilled the need of a tertium quid.

From Talks To Teachers On Psychology; And To Students On Some Of Life's Ideals by James, William