The X List

This is a collection of all the different sounds the letter X has been used to represent in language orthographies. I don't think the collection needs any particular justification; X is by far the most versatile letter of the Roman alphabet, and I am fascinated by the creative ways people have come up with of using it. As for why the letter has so many different uses, one reason is undoubtedly that in English it is more or less a “spare” letter; it could be replaced with “ks” without losing any intelligibility. Because of this, it is often used to represent “left-over” sounds that aren't easy to represent in other ways.

Plosives

/tʲ/ /ʈ/ /c/ /k/ /kʰ/ /kʷ/ /kp/ /g/ /q/ /qʰ/ /ɢ/ /ʡ/ /ʡʰ/ /ʔ/

Fricatives

/θ/ /ð/ /s/ /sʲ/ /z/ /ʃ/ /ʒ/ /ʂ/ /ʐ/ /ɕ/ /ç/ /ʝ/ /x/ /xʲ/ /xʷ/ /ɧ/ /ɣ/ /χ/ /ʁ/ /ħ/ /ʕ/ /ʢ/ /h/ /ɦ/

Affricates

/ts/ /dz/ /tʃ/ /tʃʰ/ /dʒ/ /tɬ/ /ʈʂ/ /cç/ /kx/ /ʔh/

Clusters

/ps/ /ks/ /gz/ /kʃ/ /sts/ /ʃtʃ/ /sk/ /sg/ /xs/ /ŋk/

Nasals

/ɳ/ /ɲ/ /ŋ/

Liquids

/ɾ/ /ʀ/ /я/ /ɬ/ /ɮ/ /ɫ/ /ɰ/

Non-pulmonics

/tsʼ/ /kʼ/ /ʛ/ /ǀ/ /ǁ/ /ǃ/ /ʘ/

Vowels

/ə/ /ɤ/ /i/

and one final miscellaneous use: as the syllable /kɪ/.

X has also been used in digraphs. These are too many to list individually, but of particular interest are those in which the X functions as an ad hoc diacritic; that is, it modifies the preceding sound in a regular way. This has been used to show aspiration, retroflexion, palatalisation, pharyngealisation, turning a consonant into an ejective, implosive or click, creaky voice, breathy voice, strident voice, length (after a vowel) and even stress.