ʂ U+0282, ʂ LATIN SMALL LETTER S WITH HOOK ← ʁ [U+0281] IPA Extensions ʃ → [U+0283]

Character variations

ᶳ U+1DB3, ᶳ MODIFIER LETTER SMALL S WITH HOOK ← ᶲ [U+1DB2] Phonetic Extensions Supplement ᶴ → [U+1DB4]

English Wikipedia has an article on:

voiceless retroflex fricative

Wikipedia

• IPA:

  (file)

ʂ

1. (IPA) a voiceless retroflex sibilant.
2. (superscript ⟨ᶳ⟩, IPA) [ʂ]-fricated release of a plosive (e.g. [tᶳ] or [ʈᶳ]), sometimes implying an affricate (e.g. ⟨ʈᶳ⟩ for [ʈ͡ʂ]); [ʂ]-coloring; or a weak, fleeting or epenthetic [ʂ].

• ʐ (“voiced retroflex fricative”)

• (Latin script):  Aa  Bb  Cc  Dd  Ee  Ff  Gg  Hh  Ii  Jj  Kk  Ll  Mm  Nn  Oo  Pp  Qq  Rr  Sſs  Tt  Uu  Vv  Ww  Xx  Yy  Zz

• (Letters with retroflex hook):  ᶏ  ᶐ  𝼝  ᶗ  ɖ𐞋  ᶑ𐞍  ꭦ𐞈  𝼙  ᶒ  ᶕ  ᶓ  ᶔ  ᶖ  𝼚  ʅ  ɭᶩ  ꞎ𐞝  𝼅𐞟  ɳᶯ  𝼛  Ɋɋ  Ɽɽ𐞨  ɻʵ  𝼈𐞧  Ʂʂᶳ  ᶘ  Ʈʈ𐞯  𝼉  ꭧ𐞭  𝼜  ᶙ  ʯ  ʐᶼ  ᶚ  𝼊𐞹

ʂ (upper case Ʂ)

1. (obsolete) A letter of the draft Pinyin alphabet of the 1950s; used to represent /ʂ/ and corresponds to modern ⟨sh⟩.