A phonetic complement is a phonetic symbol used to disambiguate word characters (logograms) that have multiple readings, in mixed logographic-phonetic scripts such as Egyptian hieroglyphs, Akkadian cuneiform, Linear B, Japanese, and Mayan. Often they disambiguate an ideogram by spelling out the first or last syllable of the word; occasionally (as in Linear B) they may instead abbreviate an adjective that modifies the logogram.
Written English has few logograms, primarily numerals, and therefore few phonetic complements. An example is the nd of 2nd 'second', which avoids ambiguity with 2 standing for the word 'two'. In addition to numerals, other examples include Xmas, Xianity, and Xing for Christmas, Christianity, and Crossing – note the separate readings Christ and Cross.