Un-friendliness, a negative characteristic that refers to the lack of warmth or kindness, can be expressed using different synonyms. One word that can be used to describe un-friendliness is hostility, which suggests a strong aversion or aggression towards somebody. Another term that can describe un-friendliness is coldness, which refers to an emotional distance or lack of affection. Disdain is another word that can be used to describe an unfriendly attitude, symbolizing a lack of respect or regard. Impoliteness can also describe un-friendliness, suggesting a rude or disrespectful behavior. Finally, aloofness is another synonym that can describe un-friendliness, indicating a detached or indifferent attitude towards others.