WordNet sense 1 (having or resembling repeated square indentations like those in a battlement):

castellated, crenelate, crenelated, embattled, battlemented, castled, crenellate, crenellated

WordNet sense 2 (not plain; decorative or ornamented):

fancy

WordNet sense 3 (having the central portion lower than the margin):

depressed

WordNet sense 4 (curving inward):

concave