TRENTON PERIOD
Tren"ton pe"ri*od. (Geol.)
Defn: A subdivision in the lower Silurian system of America; — so named from Trenton Falls, in New York. The rocks are mostly limestones, and the period is divided into the Trenton, Utica, and Cincinnati epochs. See the Chart of Geology.
TREPAN Tre*pan", n. Etym: [F. trépan (cf. Sp. trépano, It. trepano, trapano), LL. trepanum, fr. Gr. Trephine.]
1. (Surg.)
Defn: A crown-saw or cylindrical saw for perforating the skull, turned, when used, like a bit or gimlet. See Trephine.
2. (Mining)
Defn: A kind of broad chisel for sinking shafts.
TREPAN
Tre*pan", v. t. & i. [imp. & p. p. Trepanned; p. pr. & vb. n.
Trepanning.] Etym: [Cf. F. trépaner. See Trepan a saw.] (Surg.)
Defn: To perforate (the skull) with a trepan, so as to remove a portion of the bone, and thus relieve the brain from pressure or irritation; to perform an operation with the trepan.
TREPAN
Tre*pan", n. Etym: [See Trapan.]