abstract
abstraction
blot
blue
bone
caution
circle
corsair
crossbones
danger
dangerous
dead
deadline
death
dot
dots
dotted
evil
fear
green
hacker
halftone
hazard
horror
icon
illustration
jolly roger
mosaic
pattern
pictogram
piracy
pirate
pixel
point
poison
rebel
rip
risk
round
scary
skeleton
skull
skull crossbones
sphere
spheric
spooky
spot
toxic