صَدَأٌ

1.
verbal noun of صَدِيءَ [q. v.]. (S, M.)
2.
Also [a subst.] signifying The rust of iron, (S, M, * TA,) and of copper and the like. (Har p. 481. [But there erroneously written صداء.])
3.
Also A man slender in body; (K, TA;) light, or active, therein: its ء is said to be substituted for ع. (TA. [See صَدَعٌ; and see also صَدًى.])

Perseus ID: n23913