- weak part, weak spot, soft spot - a place of especial vulnerability
--1 is a kind of weakness
--1 has particulars: Achilles' heel; jugular; underbelly - soft spot - a sentimental affection; "she had a soft spot for her youngest son"
--2 is a kind of affection, affectionateness, fondness, tenderness, heart, warmheartedness
- fontanelle, fontanel, soft spot - any membranous gap between the bones of the cranium in an infant or fetus
--3 is a kind of orifice, opening, porta
--3 is a part of cranium, braincase, brainpan; child's body
--3 has particulars:anterior fontanelle; sphenoid fontanelle, sphenoid fontanel, sphenoidal fontanelle, sphenoidal fontanel - fontanelle, fontanel, soft spot - any membranous gap between the bones of the cranium in an infant or fetus