definition 1: to have a requirement for.
example: They need more money to support their families.
example: All animals need water to live.
example: The house needs painting and the windows need washing.
definition 2: to have or feel the necessity or obligation (to do something).
example: You need to sign the form on the front and back.
example: I need to leave now, or I’ll miss the bus.
example: I’m tired; I need to take a break.
See full entry
Note on grammar and use
When the verb “need” is followed by another verb, the second verb is most frequently in the infinitive form preceded by “to,” as in “need to sign the form,” “need to leave now,” “need to take a break”). For the meaning of “need” in the first definition, however, the second verb is often followed by the gerund (-ing) form, as in “The house needs painting” or “My hair needs trimming.” (The infinitive with the passive form can also be used for essentially the same meaning; for example, “The house needs to be painted,” My hair needs to be trimmed.” When “need” is followed by a gerund, it is most often connected with non-human subjects (e.g., “The lawn needs mowing,” “His paper needs editing,” “The dog needs brushing”), and the idea expressed is what the speaker thinks would make a necessary improvement in the subject. When the subject is a human being, the statement is often, though not always, a strong, negative judgment, as in “Those criminals need punishing!”