olive branch

Short definition from Wiktionary

Noun

1. 1
   A branch of an olive tree offered as an emblem of peace.
2. 2
   Any symbol of peace, or a peace offering to an adversary to show goodwill and in the hope of securing peace.
3. 3
   Used other than figuratively or idiomatically: A branch of an olive tree.

Verb

1. 1
   Alternative form of olive-branch.
2. 2
   To extend an olive branch; to make a peace offering; to attempt to restore peaceful relations.