expatiate

ɪkˈspeɪʃɪeɪt
ɛkˈspeɪʃɪeɪt

verb

speak or write in detail about.

she expatiated on working-class novelists

hold forth about,speak/write at length about,pontificate about,discourse on,expound,go into detail about,go on about,dwell on,expand on,enlarge on,elaborate on,amplify,embellish,spout about,sound off about,perorate on,dilate on,dissertate on