Claustral \Claus"tral\, a. [F., fr. LL. claustralis, fr. L. claustrum. See Cloister.] Cloistral. --Ayliffe
Source: Webster's Revised Unabridged Dictionary (1913)
Claustrum \Claus"trum\, n.; pl. Claustra. [L., a bolt or bar.] (Anat.) A thin lamina of gray matter in each cerebral hemisphere of the brain of man. -- Claus"tral, a.