1. A method comprising: accessing at least one of an item listing title associated with an item listing of an e-commerce website and a user search query associated with an item search request submitted to the e-commerce website; converting words in the listing title or user search query to semantic tokens in a token symbol space, based on a tokenizing process; determining, using one or more processors, that one or more of the tokens are attribute values associated with predefined attributes of one or more product categories in a product category structure of the e-commerce website; and classifying, using the one or more processors remaining ones of the tokens as candidate product type tokens associated with a global product taxonomy.