1) salt with which food is seasoned and sacrifices are sprinkled
2) those kinds of saline matter used to fertilise arable land
3) salt is a symbol of lasting concord, because it protects food from putrefaction and preserves it unchanged. Accordingly, in the solemn ratification of compacts, the orientals were, and are to this day, accustomed to partake of salt together
4) wisdom and grace exhibited in speech
Part of Speech: noun neuter
Citing in TDNT: 1:228, 36
From G251; salt; figuratively prudence: - salt.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root ἅλας; click on the second column to search for that grammatical form of the root ἅλας; click on the third column to search for that word and grammatical form; click on the total to search for the root ἅλας.