overstock vs buy in

overstock and buy in both are verbs.

Word	Noun	Adjective	Verb	Adverb
overstock	No	No	Yes	No
buy in	No	No	Yes	No

As verbs, buy in is a hypernym of overstock; that is, buy in is a word with a broader meaning than overstock:

overstock: stock excessively
buy in: amass so as to keep for future use or sale or for a particular occasion or use

Other hypernyms of overstock include stock, stock up.

overstock (verb)	buy in (verb)
stock excessively	amass so as to keep for future use or sale or for a particular occasion or use