keyword

• POS: Noun
• HYPHEN: key=word

CIDE DICTIONARY

keyword, n. 

 A word used as an entry point into an index which serves to identify files, records, texts, or other data containing the key or some related word, such as a synonym. It is a type of key{15}; as, a boolean combination of keywords is more effective for information retrieval than a single key{15}.  [PJC]

OXFORD DICTIONARY

keyword, n.
1 the key to a cipher etc.
2 a a word of great significance. b a significant word used in indexing.