The definition of imperturbable is someone that is not easily upset, angered or affected.
A level-headed person who doesn't generally get upset by things is an example of someone who is imperturbable.
that cannot be disconcerted, disturbed, or excited; impassive
Origin of imperturbableLate Latin imperturbabilis: see in-, perturb, -able
Unshakably calm and collected: “His … facial expression never deviated from the imperturbable mask” ( Molly Worthen ) See Synonyms at cool.
- im′per·turb′a·bil′i·ty im′per·turb′a·ble·ness
From Middle French imperturbable