uni·lat·er·al /ˌyü-nə-'la-tə-rəl/ adj
1: done or undertaken by one party
a unilateral mistake as to the terms
2: of, relating to, or affecting one side of a subject
3: containing a promise to perform made by only one party esp. because the other has already performed (as by paying an amount)
an option contract is unilateral
uni·lat·er·al·ly adv
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.