The Collaborative International Dictionary of English v.0.48:

Greave \Greave\, n.
   A grove. [Obs.] --Spenser.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Greave \Greave\, n. [OF. grees; cf. Sp. grevas.]
   Armor for the leg below the knee; -- usually in the plural.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Greave \Greave\, v. t. [imp. & p. p. Greaved (gr[=e]vd); p.
   pr. & vb. n. Greaving.] [From Greaves.] (Naut.)
   To clean (a ship's bottom); to grave.
   [1913 Webster]

WordNet (r) 3.0 (2006):

greave
    n 1: armor plate that protects legs below the knee [syn:
         greave, jambeau]