小母

Etymology
From 小 (o, "little," "nice") + 母 (ba, "mother")

Noun

 * 1) endearing term for a woman who is unrelated to and older than the speaker (used with honorific -さん or -さま)
 * 2) term used by a child to address an unrelated woman (used with honorific -さん)

Usage notes

 * Often found in kana form: おば