The /Ɵ/ sound is spelled with <th>. The /ʃ/ sound is spelled with <sh> or <che>.
These are two voiceless fricatives, fairly close in the mouth though one is more dental and the other more palatal and sibilant. In a way it is surprising that the contrast causes rather few problems, though this is partly because there are not many minimal pairs, giving some support to the O'Connor conjecture.
The mean density value is 1.2%. The list makes 25 semantic distinctions, a loading of 54%.
Cath cache Cath cash cloth cloche Goth gosh hath hash hearth harsh thank shank thanks shanks thanking shanking thanked shanked thaw shore thawed shored thaws shores theorist sheerest thief sheaf thieves sheaves thigh shy thighs shies thin shin thinned shinned thinning shinning thins shins thirty shirty thole shoal tholes shoals thorn shorn thought short thoughts shorts thread shred threaded shredded threading shredding threads shreds threw shrew thrift shrift thrill shrill thrilled shrilled thrilling shrilling thrills shrills thriller shriller thrive shrive thrived shrived thrives shrives thriving shriving throve shrove wealth Welsh withe wish
Credit: John Higgins