The Collaborative International Dictionary
Interambulacra
Interambulacrum \In`ter*am`bu*la"crum\, n.; pl. L. Interambulacra, E. Interambulacrums. (Zo["o]l.) In echinoderms, one of the areas or zones intervening between two ambulacra. See Illust. of Ambulacrum.
Wiktionary
interambulacra
n. (plural of interambulacrum English)