Entry 1 sense Webster, 1913 Decimeter · Dec·i·me·ter · IPA /ˈdɛ.sɪ.miːtɚ/ 01 n. A measure of length in the metric system; one tenth of a meter, equal to 3.937 inches. 1. A measure of length in the metric system; one tenth of a meter, equal to 3.937 inches.