to increase the extent, number, volume, or scope of : enlarge
to express at length or in greater detail
expandamplifyswelldistendinflatedilate mean to increase in size or volume. expand may apply regardless of the manner of increase (such as growth, unfolding, addition of parts). amplify implies the extension or enlargement of something inadequate.
phrasal verb
to speak or write about (something) in a more complete or detailed way : elaborate, on