(1) The document presents an unsupervised method called Sent2Vec to learn sentence embeddings using compositional n-gram features. (2) Sent2Vec extends the continuous bag-of-words model to train sentence embeddings by composing word vectors with n-gram embeddings. (3) Experimental results show Sent2Vec outperforms other unsupervised models on most benchmark tasks, highlighting the robustness of the sentence embeddings produced.