What is Ambiguity?

Legal Definition
In contract law, ambiguity is a term used to describe situations in which the terms of a contract have multiple definitions or refer to multiple subjects.
-- Wikipedia
Legal Definition
Contracts, construction. When au expression has been used in an instrument of writing which may be understood in more than one sense, it is said there is an ambiguity,

2. There are two sorts of amiguities of words, ambiguitas latens and ambiguitas patens.

3. The first occurs when the deed or instrument is sufficiently certain and free from ambiguity, but the ambiguity is produced by something extrinsic, or some collateral matter out of the instrument; for example, if a man devise property to his cousin A B, and he has two cousins of that name, in such case parol evidence will be received to explain the ambiguity.

4. The second or patent ambiguity occurs when a clause in a deed, will, or other instrument, is so defectively expressed, that a court of law, which has to put a construction on the instrument, is unable to collect the intention of the party. In such case, evidence of the declaration of the party cannot be submitted to explain his intention, and the clause will be void for its uncertainty. In Pennsylvania, this rule is somewhat qualified. 3 Binn. 587; 4 Binn. 482. Vide generally, Bac. Max. Reg. 23; 1 Phu. Ev. 410 to 420; 3 Stark. Ev. 1021 ; I Com. Dig. 575; Sudg. Vend. 113. The civil law on this subject will be found in Dig. lib. 50, t. 17, 1. 67; lib. 45, t. 1, 1. 8; and lib. 22, t. 1, 1. 4.
-- Bouviers Law Dictionary
Legal Definition
Doubtfulness; doubleness of meaning; indistinctness or uncertainty of meaning of an expression used in a written instrument. Nindle v. State Bank, 13 Neb. 245, 13 N. W. 275; Ellmaker v. Ellmaker, 4 Watts (Pa.) 89; Kraner v. Halsey, 82 Cal. 209, 22 Pac. 1137; Ward v. Epsy, 6 Humph. (Tenn.) 447.

An ambiguity may be either latent or patent. It ls the former, where the language employed is dear and intelligible and suggests but a single meaning, but some extrinsic fact or extrancous evidence creates a necessity' for interpretation or a choice among two or more possible meanings. But a patent ambiguity is that which appears on the face of the instrument, and arises from the defective, obscure, or insensible language used. Carter v. Holman, 60 Mo. 504; Brown v. Guice, 46 Miss. 302; Stokeley v. Gordon, 8 Md. 505; Chambers v. Ringstaff, 69 Ala. 140; Hawkins v. Garland, 76 Vn. 152, 44 Am. Rep. 158; Hand v. Hoffman, 8 N. J. Law, 71; Ives v. Kimball, 1 Mich. 313; Palmer v. Albee, 50 Iowa, 431; Petrie v. Hamilton College, 158 N. Y. 458, 53 N. E. 216.

Synonyms. Ambiguity of language is to be distinguished from unintelligibiiity and inaccuracy, for words cannot be said to be ambiguous unless their signification seems doubtful and uncertain to persons of competent skill and knowledge to understand them. Story, Contr 272. The term "ambiguity" does not include mere inaccuracy, or such uncertainty as arises from the use of peculiar words, or of common words in a peculiar sense. Wig. Wills, i74. See Ambiguity upon the factum.
-- Black's Law Dictionary
Legal Definition
Double meaning; uncertainty.
-- Ballentine's Law Dictionary