caution

definition: 
warn strongly; put on guard
sentence: 
The association cautioned that escaping moths could contaminate nearby farms and endanger their organic certification.
difficulty: 
very easy
toefl frequency: 
3
toefl classification: 
adverb: 
cautiously
adjective: 
cautious; cautionary
adverb sentence: 
Bank executives remain cautiously optimistic about the outlook.
Better to get informed and engage cautiously than to sit back and do nothing at all.
adjective sentence: 
My time in the industry gave me endless anecdotes and cautionary tales.
Even if we become more cautious in our day-to-day emailing, we sometimes forget how auto-fill works in programs we use less regularly.
verb: 
caution
verb sentence: 
He cautions other swimmers that he didn't see the shark's fin until after it first bit him.
noun: 
caution
noun sentence: 
Just use caution, and listen to your gut when you feel like something isn't quite right.