Many languages have words expressing indefinite and fictitious numbers—inexact terms of indefinite size, used for comic effect, for exaggeration, as placeholder names, or when precision is unnecessary or undesirable. One technical term for such words is "non-numerical vague quantifier". Such words designed to indicate large quantities can be called "indefinite hyperbolic numerals".

Specific values used as indefinite

The number 10,000 is used to express an even larger approximate number, as in Hebrew revâvâh, rendered into Greek as, and to English myriad. Similar usage is found in the East Asian or (lit. 10,000; ), and the South Asian lakh (lit. 100,000).

Umpteen

Umpteen, umteen or umpty is an unspecified but large number, used in a humorous fashion or to imply that it is not worth the effort to pin down the actual figure. Despite the -teen ending, which would seem to indicate that it lies between 12 and 20, umpteen can be much larger. The oldest reference to "umpty" — in a June 17, 1848 issue of the Louisville Morning Courier — indicates that at that time it was slang for empty. This is confirmed by a humorous short story in the North Carolina Hillsborough Recorder of June 30, 1852. By 1905, "umpty", in the expression "umpty-seven", had come to imply a multiple of ten. Umpty came from a verbalization of a dash in Morse code. "Umpteen", adding the ending -teen, as in "thirteen", is first attested in 1884, and has become by far the most common form. In Norwegian, ørten is used in a similar way, playing on the numbers from tretten (13) to nitten (19), but often signifying a much larger number. Similarly, though with a larger base, Portuguese has milhentos, which is derived from the words mil(har) (1000) and the suffix -entos, present in words like trezentos (300) or quinhentos (500), roughly meaning "hundred".

-illion

Words with the suffix -illion (e.g., zillion, gazillion, bazillion, jillion, bajillion, squillion, and others) are often used as informal names for unspecified large numbers by analogy to names of large numbers such as million (106), billion (109) and trillion (1012). In Estonian, the compound word mustmiljon ("black million") is used to mean an unfathomably large number. In Hungarian, csilliárd is used in the same "indefinitely large number" sense as "zillion" in English, and is thought to be a humorous portmanteau of the words csillag ("star", referring to the vast number of stars) and milliárd ("billion", cf. long scale). These words are intended to denote a number that is large enough to be unfathomable and are typically used as hyperbole or for comic effect. They have no precise value or order. They form ordinals and fractions with the usual suffix -th, e.g. "I asked her for the jillionth time", or are used with the suffix "-aire" to describe a wealthy person.

Other

A "sagan" or "sagan unit" is a facetious name for a very large number inspired by Carl Sagan's association with the phrase "billions and billions". It is not to be confused with Sagan's number, the number of stars in the observable universe.