IPA: /ˌɪn.fəˈlɪs.ɪ.təs/
KK: /ɪnˈfɛlɪsɪtəs/
Not suitable or appropriate; often used to describe something that is poorly chosen or unfortunate.
His infelicitous comment during the meeting made everyone uncomfortable.
Infelicitous is formed from "in-" (meaning not) and "felicitas" (from Latin, meaning happiness or good fortune) and the suffix "-ous" (meaning full of). The word describes a state of being not full of happiness or being unfortunate.
Think of 'not' ('in-') being 'full of happiness' ('felicitas') — that's why infelicitous means unfortunate or unhappy.