/ ˈpektərəl; NAmE / adjective , noun
■ adjective
( anatomy ) relating to or connected with the chest or breast :
pectoral muscles
■ noun
pectorals (also informal pecs ) [ pl. ] the muscles of the chest
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WORD ORIGIN
late Middle English (in the sense breastplate ): from Latin pectorale breastplate, pectoralis of the breast, from pectus , pector- breast, chest.