advice
alarm
alert
attention
beware
careful
caution
construction
danger
dangerous
design
electricity
error
excitement
exclamation
fatal
flat
graphic
hazard
hexagon
icon
illustration
important
industry
information
internet
isolated
mark
message
point
precaution
pressure
problem
risk
road
safety
secure
security
sign
signal
simple
site
street
symbol
traffic
warn
web
yellow