1. A computer-implemented method for facilitating communication, comprising: generating, for a plurality of words in a chat vocabulary, word metadata characterizing a grammatical function for the words in the chat vocabulary, wherein the words in the chat vocabulary are identified in a chat history of chat messages exchanged between users in an online virtual environment; assigning words from the plurality of words in the chat vocabulary to one or more semantic categories in an ontology; obtaining a plurality word combinability rules for combining one or more words assigned to a first one of the semantic categories with one or more words assigned to a second one of the semantic categories, based on the word metadata and the ontology, wherein at least one of the word combinability rules further specifies an allowed word order for the combinations of one or more words assigned to the first one of the semantic categories with one or more words assigned to the second one of the semantic categories and dynamically generating phrases allowed to be included in chat messages according to the plurality of word combinability rules, wherein dynamically generating phrases according to the plurality of word combinability rules comprises: receiving a text phrase composed from the chat vocabulary, the text phrase generated by a first user, evaluating the text phrase according to the plurality word combinability rules to determine whether the text phrase corresponds to a chat phrase allowed to be sent between users of an online environment, and upon determining the text phrase corresponds to an allowed chat phrase, sending the text phrase to at least a second user and adding the text phrase to a corpus of allowed chat phrases.