blotch vs colourize

blotch is a noun but colourize is not a noun.

Word	Noun	Adjective	Verb	Adverb
blotch	Yes	No	Yes	No
colourize	No	No	Yes	No

As verbs, colourize is a hypernym of blotch; that is, colourize is a word with a broader meaning than blotch:

blotch: mark with spots or blotches of different color or shades of color as if stained
colourize: add color to

Other hypernyms of blotch include color, color in, colorise, colorize, colour, colour in, colourise.

blotch (noun)	colourize (noun)
an irregularly shaped spot

blotch (verb)	colourize (verb)
mark with spots or blotches of different color or shades of color as if stained	add color to