Several parts combine into one character.

Another phonetic-loan etymology. Oracle bone 毎 originally pictured a woman with an adult hairpin — extending from 母 (mother), it meant "abundant / luxuriant". The character was hijacked phonetically to write the abstract adverb "every / each", and the original "abundant" sense largely faded except in classical contexts. Identical across 繁體 / 新字体 / 简体. Note Japanese sometimes simplified to 毎 with subtly different stroke proportions.

Mandarin: měi, dipping 3rd tone. 每 is one of Mandarin's most-used distributive determiners — it pairs with measure words and time units to mean "every / each": — 每天 (měitiān, every day) — 每周 (měizhōu, every week) — 每年 (měinián, every year) — 每个人 (měi gè rén, every person) — 每次 (měicì, every time) The pattern 每 + measure word + noun is grammatically essential in Mandarin.

Japanese: on-reading マイ (mai) is dominant — 毎日 (mainichi, every day — extremely high frequency, says daily newspaper "Mainichi Shimbun"), 毎週 (maishū, every week), 毎月 (maitsuki, every month), 毎年 (maitoshi, every year — irregular kun-reading hybrid), 毎晩 (maiban, every evening), 毎朝 (maiasa, every morning). The full 毎日/毎週/毎月/毎年 set is among the first calendar vocabulary Japanese learners drill.

Kun-reading ごと (goto) functions as a productive suffix meaning "each / every": 一日ごと (ichinichi goto, every day), 二人ごと (futari goto, every two people). Unlike 毎- prefixes, ごと goes after the count.

Memory aid: a mother with abundant hair — abundance reborrowed for "every".