companion
//kəmˈpænjən//
Noun
companionSingular
companionsPlural
1
A person who accompanies or spends time with another, especially as a friend or associate
She was my constant companion during my travels through Europe.
2
A person employed to live with and assist another, especially an elderly or disabled person
She works as a companion for an elderly woman who lives alone.
3
One of a pair of matching or complementary things
I've lost the companion to this earring.
4
A handbook or reference book on a particular subject
She bought a companion to British birds to help identify species in her garden.