Webster's Revised Unabridged Dictionary · 1913

Brier

Brier (brī"ẽr) , noun

[Old English brere, brer, Anglo-Saxon brēr, brar; compare Ir. briar prickle, thorn, brier, pin, Gael. preas bush, brier, Welsh prys, prysg.]

1.
A plant with a slender woody stem bearing stout prickles; especially, species of Rosa, Rubus, and Smilax.
2.
Figuratively: Anything sharp or unpleasant to the feelings.
The thorns and briers of reproof. — Cowper
Collocations (4)
Brier root , the root of the southern Smilax laurifolia and Smilax Walteri; -- used for tobacco pipes. See also 2nd brier.
Cat brier or Green brier , several species of Smilax (Smilax rotundifolia, etc.)
Sweet brier , See Sweetbrier.
Yellow brier , the Rosa Eglantina.

Also: Briar

Brier ({not transcribed}) , noun

1.
the white heath Erica arborea. — RHUD

Brierroot seems to have been used formerly as a term meaning root of the Smilax laurifolia and is now defined as root of the Erica arborea. Not clear when this changed. -- PJC.

2.
a smoking pipe made of the root of the brier{1}.