A notable example is WordNet (Fellbaum, 1998), which encodes a taxonomy of concepts and semantic relations between them.
wordNet has enabled a wide variety of NLP techniques such as word Sense Disambiguation (Agirre et al., 2014), information retrieval (Varelas et al., 2005), semantic similarity (Pedersen et al., 2004;Bär et al., 2013), and sentiment analysis (Baccianella et al., 2010).