Lingula \Lin"gu*la\ (l[i^][ng]"g[-u]*l[.a]), n.; pl. -l[ae] (-l[=e]). [L., a little tongue.]

1. (Anat.) A tonguelike process or part.

2. (Zo["o]l.) 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.

Source: Webster's Revised Unabridged Dictionary (1913)