The meaning of the word frigid is something that is very cold in temperature. Frigid is a word that is used as an adjective in the English language. Adjectives modify nouns or other adjectives. Some synonyms, or words that have similar meanings include: stiff, unfeeling, remote and reserved.
As you can see from the synonyms although frigid can refer to the actual temperature of something it often refers to the disposition of a person. You will often see a person with a cold and hardened heart being referred to as frigid. This also a term that you will often hear used when referring to someone that is romantically unapproachable as well.