IPA: /ˌɪnɪkˈsprɛsɪv/
KK: /ɪnˈɛkspresɪv/
Not showing any feelings or emotions; dull and flat in appearance or expression.
His face was inexpressive, making it hard to tell what he was thinking.
Inexpressive → It is formed from "in-" (meaning not) and "expressive" (from Latin "expressivus", meaning to press out or convey). The word "inexpressive" means not conveying or showing emotion or feeling.
Think of 'not' ('in-') being combined with 'conveying' ('expressive') to remember that inexpressive means not showing feelings.