'To brush up' definitions:

Definition of 'To brush up'

From: GCIDE

Brush \Brush\, v. t. [imp. & p. p. Brushed (br[u^]sht); p. pr. & vb. n. Brushing.] [OE. bruschen; cf. F. brosser. See Brush, n.]
1. To apply a brush to, according to its particular use; to rub, smooth, clean, paint, etc., with a brush. "A' brushes his hat o' mornings." --Shak. [1913 Webster]
2. To touch in passing, or to pass lightly over, as with a brush. [1913 Webster]
Some spread their sailes, some with strong oars sweep The waters smooth, and brush the buxom wave. --Fairfax. [1913 Webster]
Brushed with the kiss of rustling wings. --Milton. [1913 Webster]
3. To remove or gather by brushing, or by an act like that of brushing, or by passing lightly over, as wind; -- commonly with off. [1913 Webster]
As wicked dew as e'er my mother brushed With raven's feather from unwholesome fen. --Shak. [1913 Webster]
And from the boughts brush off the evil dew. --Milton. [1913 Webster]
To brush aside, to remove from one's way, as with a brush.
To brush away, to remove, as with a brush or brushing motion.
To brush up, to paint, or make clean or bright with a brush; to cleanse or improve; to renew. [1913 Webster]
You have commissioned me to paint your shop, and I have done my best to brush you up like your neighbors. --Pope. [1913 Webster]