Lingula

Part of speech: noun (n.)

1. A tonguelike process or part.

2. Any one of numerous species of brachiopod shells belonging to the genus Lingula, and related genera. See Brachiopoda, and Illustration in Appendix. Lingula flags (Geol.), a group of strata in the lower Silurian or Cambrian system of Wales, in which some of the layers contain vast numbers of a species of Lingula.