1) a whip, scourge
2) metaphorically a scourge, plague
2a) a calamity, misfortune, especially sent by God to discipline or punish
Part of Speech: noun feminine
Citing in TDNT: 4:518, 571
Probably from the base of G3145 (through the idea of contact); a whip (literally the Roman flagellum for criminals; figuratively a disease): - plague, scourging.
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 μάστιξ; click on the second column to search for that grammatical form of the root μάστιξ; click on the third column to search for that word and grammatical form; click on the total to search for the root μάστιξ.