I am currently looking for a list of adjectives that I can use as a seed for a machine learning model. These do not need to be annotated. Are there any open source lexicons that exist which could be used for this purpose?
You can use WordNet's adjectives:
WordNet® is a large lexical database of English. Nouns, verbs, adjectives and adverbs are grouped into sets of cognitive synonyms (synsets), each expressing a distinct concept.
You can find them in the archive or retrieve them programatically with tools such as NLTK. More detailed explanations about the adjectives in WordNet can be found in the following paper:
- Gross, Derek, and Katherine J. Miller. "Adjectives in wordnet." International Journal of lexicography 3.4 (1990): 265-277. APA
You can extract adjectives (for many different languages, not only English) from the Wiktionary. Wiktionary has a higher coverage of the vocabulary than WordNet.