IPA: /ˌʌnɪˈmoʊʃənl/
KK: /ʌnɪˈmoʊʃənl/
Not showing or expressing strong feelings or emotions; calm and rational.
She remained unemotional during the meeting, even when discussing difficult topics.
Unemotional → It is formed from "un-" (meaning not) and "emotional" (from Latin "emotio" meaning a movement or stirring). The word "unemotional" means not showing or feeling emotions, indicating a lack of emotional response.
Think of 'not' ('un-') feeling or showing any 'stirring' ('emotio') — that's why unemotional means lacking emotion.