IPA: /ˌmɪlɪˈdɪɡri/
KK: /mɪlɪdɪˈɡri/
A unit of temperature that is one-thousandth of a degree.
The temperature increased by five millidegrees during the experiment.
Millidegree → It is formed from "milli-" (meaning one thousandth) and "degree" (from Latin "gradus", meaning step or degree). The word "millidegree" refers to one thousandth of a degree, often used in temperature measurements.
Think of 'milli-' meaning one thousandth, and 'degree' as a step in measurement — so a millidegree is a tiny step, specifically one thousandth of a degree.
No commonly confused words.