clean, easy, quick
fresh
vultures sensing a fresh kill

fish (AmE)
the worst fish kill in recorded history

make
The lion made a quick kill.

be in at (BrE)
I didn't even see the fox, let alone be in at the kill.

close in for, go in for, move in for
The hunters moved in for the kill.

at the kill (BrE)
The meat is divided up among all those present at the kill.

for the kill
The animal crouched down, getting ready for the kill.

outright
He has fought more than fifty bulls, killing three outright.

almost, nearly
instantly
quickly
The animals are killed quickly and humanely.

slowly
The poison was slowly killing her.

eventually, finally
the camp guards who tortured and eventually killed her

accidentally, inadvertently
deliberately, intentionally
I don't believe that he intentionally killed her.

allegedly
his trial for allegedly killing his wife

unlawfully (BrE,law)
The inquest concluded that he was unlawfully killed.

needlessly
the number of people needlessly killed by hospital infections

indiscriminately
The terrorists had shown their willingness to kill indiscriminately.

systematically
The militias are systematically killing and raping civilians.

brutally
There were reports of people brutally killed.

want to
be prepared to
They are quite prepared to kill to achieve their ends.

threaten to
be going to, intend to, mean to, plan to
He knew they meant to kill him.
What if they really do plan to kill us?
Dad's going to kill me when he finds out. (figurative)

plot to
They plotted to kill the dictator.

attempt to, seek to, try to
help (to)
make sb
The situation must have been really awful to make her kill herself.

admit killing sb, admit to killing sb, deny killing sb
He admitted killing her but said it was unintentional.

be accused of killing sb, be charged with killing sb
be killed in sth
soldiers killed in battle

be tragically killed
Their daughter was tragically killed in a road accident.

Kill is used with these nouns as the subject:
army, avalanche, blast, bomb, bullet, crash, disease, earthquake, explosion, fanatic, fumes, killer, lion, military, missile, mob, monster, mould, murderer, shot, troops, violence, virus

Kill is used with these nouns as the object:
animal, bacteria, bill, cattle, cell, chance, chicken, civilian, cow, demonstrator, elephant, embryo, enemy, engine, firefighter, flea, germ, hope, hostage, infection, insect, lamb, lover, monster, mood, mosquito, mouse, murderer, pain, parasite, pest, pig, prey, speed, time, weed, whale