These words often are taken to mean the same thing—which in some contexts they indeed do. When used to refer to test results or experimental findings, for example, both words are properly used to indicate uncertainty, ie, that the findings can be understood in more than one way.

However, a distinction comes to bear when one is referring to statements, either written or oral. Although both words also can properly be used when referring to a statement subject to more than one interpretation, accepted usage holds that ambiguous is the proper choice if the resulting uncertainty seems unintentional^1(p39) and that equivocal is the way to go if the uncertainty seems to have been intentionally introduced to confuse or deceive.^1(p423) The deceptive intent is key, and it is worth noting that whereas the verb equivocate is an accepted word, ambiguate is not.

Deceptive intent might be inferred from the immediate context of surrounding statements. Often, however, intent is inferred from the larger context, ie, the history of the issue under discussion or the (perceived) character of the person making the statement. Given the latter means of inference, it is not surprising that the use of equivocal to refer to deceptive statements has been accepted since the late 1700s—about the time that the word also came to be commonly used to describe persons believed “[d]oubtful in character or reputation; liable to unfavorable comment or description; questionable; suspicious.”^2(p527) Equivocal is still occasionally used when referring to such persons, but current usage, particularly in the social media, tends to favor terms somewhat more colorful.

Equivocal also can imply that a person has used ambiguous language in a qualifying way to avoid personal commitment to the statement made.^1(p423) This meaning, however, although a bit more neutral than the meaning already noted, still hints at something less than savory. In short, although using ambiguous and equivocal interchangeably to describe a statement will be correct in some instances, writers tempted to use equivocal in place of ambiguous would do well to remember that the former has additional connotations often freighted with “nasty overtones.”³

Perhaps because clarity and certainty are seldom used for deceptive purposes, matters are less complicated in negative constructions: unambiguous and unequivocal both indicate that a test result or a statement has only one interpretation. However, because equivocal carries negative connotations, unequivocal is often used to emphasize a lack of deceptive intent.

As a side note, another word, unequivocable, has been used interchangeably with unequivocal since the early 1900s.^2(p2166) How this monster came to be is a matter of some conjecture, but it likely arose either from innocent confusion over the proper spelling and pronunciation of equivocal or from a desire to use a loftier-sounding word (although it is difficult to imagine an instance in which unequivocal would not be lofty enough). In any case, unequivocable and its variants are often considered nonstandard.^1(p1366)

The bottom line:

● Referring to test results or experimental findings having more than one interpretation? Ambiguous and equivocal are both correct, but it is worth noting that the latter can have negative overtones and is perhaps best avoided unless the reporting of results seems intentionally unclear.

● Referring to a statement having more than one interpretation? Remember that all equivocal statements are ambiguous, but not all ambiguous statements are equivocal. If the statement seems intentionally unclear with the goal of distancing or deceiving, use equivocal.

● Unambiguous and unequivocal both indicate that something has only one interpretation, although when describing a statement unequivocal is sometimes used to emphasize an absence of deceptive intent.

● Unequivocable, while found in some dictionaries, is often considered nonstandard and should probably be avoided.—Phil Sefton, ELS

1. Merriam-Webster’s Collegiate Dictionary. 11th ed. Springfield, MA: Merriam-Webster Inc; 2003.

2. The Compact Oxford English Dictionary. 2nd ed. Oxford, England: Oxford University Press; 1991.

3. Ambiguous, equivocal. In: Bernstein TM. The Careful Writer: A Modern Guide to English Usage. New York, NY: Athaneum; 1985:38.