tart vs sourish

tart is a noun but sourish is not a noun.

Word	Noun	Adjective	Verb	Adverb
tart	Yes	Yes	No	No
sourish	No	Yes	No	No

As adjectives, tart and sourish are synonyms defined as:

Other synonyms of tart include lemonlike, lemony, tangy.

tart (noun)	sourish (noun)
a small open pie with a fruit filling
a pastry cup with a filling of fruit or custard and no top crust
a woman who engages in sexual intercourse for money

tart (adjective)	sourish (adjective)
tasting sour like a lemon	tasting sour like a lemon
harsh