From Longman Dictionary of Contemporary Englishldoce_101_ffirst aid kitˌfirst ˈaid kit noun [countable] 
MHa special bag or box containing bandages and medicines to treat people who are injured or become ill suddenly
MHa special bag or box containing bandages and medicines to treat people who are injured or become ill suddenlyExamples from the Corpus
first aid kit• First Aid Kit Every competitor should have his own first aid kit.• There is little point in having a first aid kit on the ground floor if you cut your foot badly upstairs.• The tail section housed emergency rations and first aid kit.• Sec., Ken Lucas in support with a car carrying liquid refreshments and first aid kit!• Our man comes, of course, complete with rescue equipment, first aid kit, space blanket, etc.• Lifebuoys, offshore flares, two fire extinguishers, first aid kit.• Odd-Knut fetches his first aid kit, and I get ours. 