Meaning

1. to need (to want strongly; to feel that one must have something) [with genitive or (proscribed) accusative] or
2. to need (to have an absolute requirement for) [with genitive or (proscribed) accusative]
3. (colloquial) to need, to have to (to be obliged or required to do something)
4. to need each other (to want one-to-one contact or mutual support as necessary in a given situation)
5. to need each other (to not able to function properly one without the other)