イク, そだ.つ, そだ.ち, そだ.てる, はぐく.む, やす
bring up, grow up, raise, rear
JLPT3 G3 S8 F369
The relevant seal inscription form of the top element (now written ?)# is 子 child upside down, indicating a fetus filling then passing through the birth canal → *breeding*. *Raise*, *upbringing* and *growth* are associated meanings, with *foster* (growth) by extension. The addition of 肉 flesh is for emphasis/clarification.
[Full Kanji Etymology List]