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uk â /hem/ us â /hem/. âº the edge of a piece of cloth, such as the bottom edge of a skirt or dress, that is folded over and sewn so that it does not develop loose threads: I took the hem up/let the hem down. Thesaurus: synonyms and related words. Parts of clothes.
(hÄm) The deep red, nonprotein, iron-containing component of hemoglobin that carries oxygen. Heme is a porphyrin with an iron atom at its center. One of the free valence electrons of the iron atom of heme is bound to the hemoglobin molecule, while the other is available for binding to an oxygen atom. A hemoglobin molecule contains four hemes. Chemical formula: C34H32FeN4O4.