Is one or more letters or syllables added to the end of a word or word part to create a new word?

Not a very clear question but usually a suffix creates a verb tense or an adjective or adverb from the root Word. Not really a new Word but a method of using the original Word. E.g. quick (adj.) to quickly (adv.).

You can add a whole Word as a suffix to make a compound related to the original, though often with a hyphen. E.g. cake-tin, a metal container for baking or storing cakes.