Which word denotes a change in shape or form?

The term that denotes a change in shape or form is "transmogrify." This word specifically refers to transforming something in a way that is often surprising or fantastical, emphasizing a dramatic or bizarre change. For example, it might be used in contexts where an object or person changes into something completely different, highlighting the alteration in its appearance or characteristics.

Other options can imply change but carry different nuances. "Transform" suggests a more general change, often in structure or appearance, without the bizarre or whimsical connotation. "Transmute" relates to changing one substance into another, emphasizing a level of chemical or elemental change rather than straightforward appearance. "Transition" refers to the process of changing from one state to another and does not necessarily denote a change in form or shape but rather a movement or shift over time. Thus, "transmogrify" is the most fitting choice when specifically referring to a change in shape or form, particularly with an element of surprise or fun.