1) a monument or memorial to perpetuate the memory of any person or thing
2) a sepulchral monument
3) a sepulchre or tomb
Part of Speech: noun neuter
Citing in TDNT: 4:679, 596
From G3415; a memorial, that is, sepulchral monument (burial place): - grave, sepulchre, tomb.
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 μνῆμα; click on the second column to search for that grammatical form of the root μνῆμα; click on the third column to search for that word and grammatical form; click on the total to search for the root μνῆμα.