叔母
おば · oba · JLPT N2 · noun
aunt
叔 (younger uncle) + 母 (mother) = a younger mother, i.e. an aunt
Kanji etymology: 叔 marks the younger of two siblings, here one's parent's younger sibling, and 母 means mother. Together they name a parent's younger sister, the aunt who is a 'younger mother'.
母 — pictograph of kneeling woman with two breast dots
母 is a pictograph derived from 女 (woman) with two added dots representing breasts, marking a nursing mother. The earliest oracle bone forms show a kneeling figure with prominent dots on the chest. The meaning has stayed remarkably stable, denoting 'mother' and by extension 'female' or 'source/origin'.