buck up

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• interjection idiomatic Cheer up; take courage; take heart.
• interjection idiomatic, dated Hurry up; make haste.
• verb idiomatic, intransitive To become encouraged, reinvigorated, or cheerful; to summon one's courage or spirits.
• verb idiomatic, transitive To encourage or refresh; to hearten.
• verb idiomatic, intransitive, dated, early 1900's To dress oneself up smartly; compare (obsolete) buck ("a fop, dandy")
• verb idiomatic, transitive, colloquial To pass on to higher authority for resolution. See also pass the buck.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb gain courage