A noun/suffix meaning '-ish' or 'tending to ...', indicating a tendency or slight degree (often with a somewhat negative or uneasy nuance).
最近、疲れ気味で夜よく眠れない。
Lately I've been feeling a bit tired and can't sleep well at night.
風邪気味だから今日は早く休んだほうがいい。
You're coming down with a cold, so you'd better rest early today.
面接では緊張気味でうまく話せなかった。
I was a bit nervous at the interview and couldn't speak well.