1) to preserve through danger, to bring safely through
1a) to save, i.e. cure one who is sick, bring him through
2) to save, keep from perishing
3) to save out of danger, rescue
Part of Speech: verb
From G1223 and G4982; to save thoroughly, that is, (by implication or analogy) to cure, preserve, rescue, etc.: - bring safe, escape (safe), heal, make perfectly whole, save.
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 διασῴζω; click on the second column to search for that grammatical form of the root διασῴζω; click on the third column to search for that word and grammatical form; click on the total to search for the root διασῴζω.