Learning the meaning of new words is an important aspect of human language. But after learning, we must be able to recall these meanings and integrate them with other lexical items accordingly. In the present study we hypothesize that reactivating a novel word´s meaning could be a key mechanism for a successful lexical integration. We performed a series of online studies analyzing the contribution of memory reactivation to: lexical integration (Study 1) and updating of a word’s meaning (Study 2). Native speakers of Spanish (18-35 years) learned a list of low-frequency Spanish words with their definitions. The following day, Reactivated groups were exposed to a reminder consisting of the list of words but without their definitions. Non Reactivated groups did not receive a reminder. In Study 1 (N=112), memory retention was evaluated 48 h after training with a cued-recall test or a semantic judgment task. In Study 2 (N=81), participants learned new information for each of the words’ definitions and memory retention was evaluated 48 h after training using a cued-recall test. Results of Study 1 show a significant enhancement of words’ memory and semantic recognition speed in the Reactivated group. Study 2 reveals a significant enhancement of the new information’s memory that increases according to the reactivation strength of each word. Taking into account both results, we demonstrated the importance of memory reactivation for constructing and updating our mental dictionary.