To take precautions is to act in advance against something that might go wrong. Helmet on, spare fuse in the drawer, a copy of the passport in another bag.
It is nearly always plural — one of them sounds like a technicality, several sound like sense. It takes against: against frost, against fire, against theft. The word carries a faint official tone, so a notice board says it where a friend would say be careful, and in a health context the plural alone carries a meaning of its own that everybody understands and nobody spells out.
1phrasetake precautionsTo act in advance against a possible danger.
“Anyone climbing here should take precautions.”
take precautions is an act of caution.
Practised in Common Word Pairs