It depends who you ask. Some people say that rhyme is about the last vowel sound at the end of a word. Others say it is the last syllable. A third group say it is only the last stressed syllable.
My view? It is what you want it to be if it sounds right to you. Try these examples out. On the first definition 'purple' could be said to rhyme with 'subtle'. (Yes, some people also argue for a consonant + vowel sound definition, but that gets complicated.) What about 'purple' and 'turtle'? Do 'orange' and 'arrange' rhyme? Most people would argue 'go', 'slow', 'blow' and 'hoe' rhyme.
I looked at the OED and it gives various definitions for the noun, including 'correspondence of sounds'.