unfreundlich
unfriendly
Describes a person or their behavior as not nice, dismissive, or impolite.
Der Verkäufer war am Telefon sehr unfreundlich zu mir.
The salesperson was very unfriendly to me on the phone.

unfriendly
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unfriendly
Describes a person or their behavior as not nice, dismissive, or impolite.
Der Verkäufer war am Telefon sehr unfreundlich zu mir.
The salesperson was very unfriendly to me on the phone.

The word has a simple structure: the prefix 'un-' negates the adjective 'freundlich' (friendly). 'Un-' is a very common prefix in German for expressing the opposite.
Sein Verhalten war nicht nur unfreundlich, sondern auch unprofessionell.
His behavior was not only unfriendly, but also unprofessional.
You can tell whether a person or a thing is meant from the noun. If 'unfreundlich' (unfriendly) refers to a person or their behavior, it means 'impolite'. If it refers to the weather, a place, or colors, it means 'uncomfortable' or 'unwelcoming'.
Der Beamte gab mir eine sehr unfreundliche Antwort.
The official gave me a very unfriendly answer.
If you want to say whom a person is unfriendly to, use the preposition 'zu' followed by the dative. The structure is: 'jemand ist unfreundlich zu jemandem' (someone is unfriendly to someone).
Warum bist du heute so unfreundlich zu deinen Kollegen?
Why are you so unfriendly to your colleagues today?
In the meaning of 'inhospitable' or 'unwelcoming', the adjective is often used to describe the weather, an atmosphere, or an environment. Typical phrases are 'unfreundliches Wetter' (unwelcoming weather), 'eine unfreundliche Gegend' (an unwelcoming area), or 'eine unfreundliche Atmosphäre' (an unwelcoming atmosphere).
Wegen des unfreundlichen Wetters wurde das Picknick abgesagt.
Because of the unwelcoming weather, the picnic was canceled.
nice / dear
'lieb' and 'unfreundlich' both describe how a person or their behavior comes across to others. Here they are opposites. A lieb person is nice, friendly, and means well. An unfreundlich person seems dismissive, cold, or impolite. You use 'lieb' when someone kindly helps or deals with others in a pleasant way. 'unfreundlich' fits when someone reacts badly, does not say hello, or speaks very harshly.

Beim Einkaufen war der Verkäufer unfreundlich und hat kaum geantwortet.
While shopping, the salesperson was unfriendly and barely answered.
Nina ist sehr lieb, weil sie dem neuen Schüler sofort hilft.
Nina is very kind because she immediately helps the new student.