Is there a verb that means, "to inject venom," or, "to inject poison?"
Those are two separate things. The verb form of poison encompasses the latter. From Merriam-Webster:
1 a : to injure or kill with poison; b : to treat, taint, or impregnate with or as if with poison
Curiously, M-W defines envenom as:
1 : to make poisonous
The freedictionary.com defines envenom as:
- to fill or impregnate with venom; make poisonous
(of a snake, spider, insect, etc.) poison by biting or stinging.
‘these observations suggest that the spiders envenomate their prey’
(Oxford Living Dictionaries)
The fairly archaic word venenate might fit the bill:
ven·e·na·tion | \ ˌven-ə-ˈnā-shən \
Medical Definition of venenation
: the condition or process of being poisoned especially by a venom of animal origin
Other Words from venenation
venenate \ ˈven-ə-ˌnāt \ verb venenated; venenating
B2 to put poison in someone's food or drink:
'He said that someone had poisoned his coffee.'
1.1 Adulterate or contaminate with poison.
‘the Amazon basin is being poisoned by the mercury used by gold prospectors’
or My example from comments
she poisoned the apple and waited for snow white to eat it