n. pl. am·bu·lac·ra (-lăkrə, -lākrə) One of the five radial areas on the undersurface of the starfish and similar echinoderms, from which the tube feet are protruded and withdrawn. [Latin ambulācrum, walk planted with trees, from ambulāre, to walk; see ambhi in the Appendix of Indo-European roots.] am′bu·lacral adj. (click for a larger image) ambulacrumventral view of a starfish arm |
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.