Meaning of keyword

key•word

1. a word that serves as a key, as to the meaning of another word, a sentence, passage, or the like: Search the database for the keyword “Ireland.”
2. a word used to encipher or decipher a cryptogram, as a pattern for a transposition procedure or the basis for a complex substitution.
3. Also calleda significant or memorable word or term in the title, abstract, or text of an item being indexed, used as the index entry.