48 CFR §15.001

As used in this part— Deficiency is a material failure of a proposal to meet a Government requirement or a combination of significant weaknesses in a proposal that increases the risk of unsuccessful contract performance to an unacceptable level. Proposal modification is a change made to a proposal before the solicitation closing date and time, or made in response to an amendment, or made to correct a mistake at any time before award. Proposal revision is a change to a proposal made after the solicitation closing date, at the request of or as allowed by a contracting officer, as the result of negotiations. Weakness means a flaw in the proposal that increases the risk of unsuccessful contract performance. A “significant weakness” in the proposal is a flaw that appreciably increases the risk of unsuccessful contract performance.