乳
ニュウ, ちち, ち
milk, breasts
JLPT2 G6 S8 F1289
The relevant seal inscription form is
孚
# (envelop/enclose) +
乙
here a shape indicator to suggest a breast → (mother's) *milk* enclosed in a *breast* → *feed* (a baby); *infantile*.
[Full Kanji Etymology List]