A synonym is a word or phrase, which has exactly or nearly the same meaning as another word or phrase in the same language, e.g., Happy is a synonym of glad, joyful, etc. Such words which have the same or related meaning are known as synonyms of one another.
Brief means short, concise, etc.
A vent is an opening or outlet for air, gas or liquid.
Canny means clever, shrewd, etc.
Alert means watchful, attentive, etc.
Distant means far-away, far-off, etc.