Main Entry: ad·a·man·tine

Pronunciation: \ˌa-də-ˈman-ˌtēn, -ˌtīn, -ˈman-t^ən\

Function: adjective

Etymology: Middle English, from Latin adamantinus, from Greek adamantinos, from adamant-, adamas

Date: 13th century

1 : made of or having the quality of adamant
2 : rigidly firm : unyielding <adamantine discipline>
3 : resembling the diamond in hardness or luster