Real Dictionary

-form in American English
having the form of; shaped like
combining form: a combining form meaning “having the form of ”

-form in British English
combining form in adjective: having the shape or form of or resembling

form
countable noun: A form of something is a type or kind of it.
countable noun: The form of something is its shape.
countable noun: When something can exist or happen in several possible ways, you can use form to refer to one particular way in which it exists or happens.
verb: When a particular shape forms or is formed, people or things move or are arranged so that this shape is made.

form in American English
the shape, outline, or configuration of anything; structure as apart from color, material, etc.
noun: external appearance of a clearly defined area, as distinguished from color or material; configuration

form in British English
noun: (in the philosophy of Plato) an ideal archetype existing independently of those individuals which fall under it, supposedly explaining their common properties and serving as the only objects of true knowledge as opposed to the mere opinion obtainable of m
noun: the shape or configuration of something as distinct from its colour, texture, etc
verb: to give shape or form to or to take shape or form, esp a specified or particular shape