From Longman Dictionary of Contemporary Englishif/when (you’re) in doubtif/when (you’re) in doubtADVISEused when advising someone what to do if they are uncertain about something If in doubt, consult your doctor. → doubt
Examples from the Corpus
if/when (you’re) in doubt• When in doubt or when scared or when pressed, count.• When in doubt, you take.• Always be ready to release during the take-off run and if in doubt, abandon the take-off.• But if in doubt, ask!• The soldier's motto, Price had told the men: when in doubt go forward.• The first is a good motto: when in doubt, take them out.• In other words, if in doubt, don't take a chance. 