Definition of OK yah in English:

OK yah

exclamation

British
slang
  • In representations or imitation of upper or upper-middle-class speech (originally that of ‘Sloane Rangers’): yes. Also as noun: an utterance of this.

adjective

British
slang
  • Of, relating to, or designating a person who is conspicuously or unselfconsciously upper or upper-middle-class in speech; ‘posh’, ‘Sloanie’.

Origin

1980s; earliest use found in The Times. From OK [interjection¹, noun², adverb] + yah.

Pronunciation

OK yah

/ˌəʊkeɪ ˈjɑː/