insu

Middle French adjective insceu (“unknown”), corresponding to in- +‎ su.

• IPA^(key): /ɛ̃.sy/

insu m (uncountable)

1. (in set phrases) ignorance

   Il était content à son insu.

   He was happy without realising it.

This noun is now found only in the construction à l’insu de … (“unbeknownst to …, without …’s knowledge”), or, if the object is a personal pronoun, à [possessive pronoun] insu (“unbeknownst to [objective pronoun], without [possessive pronoun] knowledge”).

• “insu” in le Trésor de la langue française informatisé (The Digitized Treasury of the French Language).

• nuis, unis