na-adjective
Loanword from English 'abnormal'. Used similarly to the English word, often in formal or technical contexts, but also in everyday speech to describe something unusual or deviant.
彼の行動は少しアブノーマルだ。
His behavior is a little abnormal.
この気温はアブノーマルです。
This temperature is abnormal.
異常 is the native Japanese word for 'abnormal' and is more common in formal or serious contexts. アブノーマル carries a slightly more colloquial or psychological nuance.
Borrowed from English 'abnormal'.