One half is one of the few fractions which are commonly expressed in natural languages by suppletion rather than regular derivation.
In English, for example, compare the compound "one half" with other regular formations like "one-sixth".
It is acceptable to write one half as a hyphenated word, one-half.
A number raised to the power of one half is equal to its square root.
The "one-half" symbol has its own code point as a precomposed character in the Latin-1 Supplement block of Unicode, rendering as ½.
The reduced size of this symbol may make it illegible to readers with relatively mild visual impairment; consequently the decomposed forms 1⁄2 or 1/2 may be more appropriate.