Answer: Subsidary
Explanation: The term "subidiary" refers to something that is subordinate or secondary to a larger entity or main object. In the context of the question, a "form existing inside of a larger form" could be considered a subsidiary form, where the larger form is the main entity and the smaller form is a subordinate element within it. For example, in a musical composition, a subsidiary form could be a theme or motif that is repeated throughout the piece, while the larger form could be the overall structure or arrangement of the music.