In text-to-speech synthesis, a non-standard word is a sequence of characters between a pair of word boundaries that is not found nor is easily derived from words in a standard dictionary of the language.
Examples of non-standard words are:
- cardinal numbers: 123 (one hundred and twenty-three)
- ordinal numbers: 13th (thirteen)
- roman numbers: Charles ||| (Charles third)
- money amounts: 20.10€ (twenty euros and ten cents)
- percentage: 3.5% (three point five per cent)
- dates: 1755/11/1 (first of November of seventeen fifty-five)
- years: the 90's (the nineties)
- time: 12:10 (twelve ten)
- symbols: + (plus)
- abbreviations: Av. (avenue)
- acronyms: NY (New York), GPU (gee pee u)
Many non-standard words can have multiple meanings corresponding to different conversions to standard words. This meaning is called the [[semiotic class]] of the word.