Irregular spelling
From Teflpedia
Irregular spelling (//), where the pronunciation of a word does not match its spelling.
English is noted for having a high degree of irregular spelling compared to other languages that follow the alphabetic principle. This irregularity mostly affects high-frequency words. This presents problems for some English language learners, as a first or second language, particularly those having dyslexia. Good English readers learn to recognise common irregular spellings as sightwords. English writers have to memorise the spellings of a large number of common words.
A spelling in one dialect or accent that is irregular may not be in another dialect or accent. The flipside of irregular spelling is irregular pronunciation.