minute (i.e. extremely small); infinitesimal
微 · 13 strokes
Phonosemantic compound. 彳 represents the meaning and 𢼸 represents the sound. Based on the original meaning "go out and hide". The meaning later shifted to "conceal" and "tiny".
小 · 3 strokes
Depicts three small dots, representing the meaning "small". Originally the same character as 少. The small dots possibly represent grains of sand (沙).