Is there a term for words like "wanna" or "gonna" which have been shortened from their originals of "want to" and "going to"?
gonna /ˈgɒnə / informal ▸ (contraction) going to: so what you gonna do now?
wanna /ˈwɒnə / informal ▸ (contraction) want to; want a: you wanna know how low I've stooped? I wanna guitar. OxfordLivingDictionaries