1) this (very) day)
2) what has happened today
Part of Speech: adverb
Citing in TDNT: 7:269, 1024
Neuter (as adverb) of a presumed compound of the article G3588 ("tau" changed to "sigma") and G2250; on the (that is, this) day (or night current or just passed); genitively now (that is, at present, hitherto): - this (to-) day.
|(ἐχθὲς καὶ σήμερον καὶ εἰς τοὺς αἰῶνας) always||67.87|
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 σήμερον; click on the second column to search for that grammatical form of the root σήμερον; click on the third column to search for that word and grammatical form; click on the total to search for the root σήμερον.