System and method for providing an instant messenger service, and communication terminal and communication method therefor

Disclosed are an intelligent emotional word expanding apparatus and expanding method therefor. The intelligent emotional word expanding apparatus according to one embodiment of the present invention comprises a word dictionary storing module which classifies emotional words into items including emotion class, similarity, positivity or negativity, and/or emotional intensity, and storing the items as an emotional word dictionary, and storing neutral words and an accumulated number of calls as a neutral word dictionary; an emotion-inferring module which captures words and phrases of a sentence logged by a user and converts the words and phrases into a basic format, and infers emotions on the basis of the converted words or phrases and the emotional word dictionary; and a word expanding module which determines whether a word or a phrase is neutral on the basis of the neutral word dictionary if the emotion inference by the emotion-inferring module has failed, measures the relationship to the emotion class in an electronic emotion dictionary if the word or phrase is not neutral, and adds the word or phrase to the emotional word dictionary if the measured relationship to the emotion class exceeds a threshold value.