IPA: //ˈmɪdˌmʌnθ//
KK: /mɪdˈmʌnθ/
Happening in the center part of a month, not at the start or the end.
The midmonth report showed a significant increase in sales.
Midmonth → It is formed from "mid-" (meaning middle) and "month" (from Old English "mōnaþ", meaning a period of time based on the lunar cycle). The word "midmonth" refers to the middle of a month.
Think of being in the 'middle' ('mid-') of a 'month' — that's what midmonth means.
No commonly confused words.