Word Study
yeah
WORDNET DICTIONARY
Adverbial yeah has 1 sense
- yeah(r = adv.all) yea - not only so, but; "I therein do rejoice, yea, and will rejoice"
OXFORD DICTIONARY
yeah, adv. colloq. yes.
Idiom
oh yeah? expressing incredulity.
Etymology
casual pronunc. of YES
For further exploring for "yeah" in Webster Dictionary Online