All 6 Uses

taint
in
Breaking Dawn, by Meyer
(Auto-generated)

Sure, the pack was rough on her, but she brought it all on herself with the bitterness that tainted her every thought and made being in her head a nightmare.†
Book 2 *

tainted = spoiled or contaminated
...That smell made my throat burn dryly, a faint echo of the venom burn, though the scent was tainted by the bite of chlorine and ammonia.†
Book 3
Now that I had given the thirst my attention, it seemed to taint every other thought in my head, leaking into the more pleasant thoughts of running and Edward's lips and kissing and...scorching thirst.†
Book 3

taint = to spoil something so it is not desirable
"Safer for Renesmee," Edward continued, "if the choice to believe our story about her is not tainted by an association with werewolves."†
Book 3

tainted = spoiled or contaminated
The spectrum of light I saw still seemed tainted with crimson.†
Book 3
Though I was in a hurry to be done with this depressing necessity and back with my family, J seemed careful to keep himself untainted by his baser associations; I had a feeling a handoff in the dark parking lot would offend his sensibilities.†
Book 3

untainted = not spoiled or contaminated

standard prefix: The prefix "un-" in untainted means not and reverses the meaning of tainted. This is the same pattern you see in words like unhappy, unknown, and unlucky.

Definitions:

(1) (taint)
to spoil something so it is not desirable -- as when bacteria contaminates a food; or as when a rumor makes people distrust a person
(2) (meaning too rare to warrant focus)
Much more rarely, taint is used in a non-negative way to refer to a trace of something.