1) a sending away
1a) of the sending off of a fleet
1b) of consuls with an army, i.e. of an expedition
2) a sending away, i.e. a dismissal, release
3) a thing sent, especially of gifts
4) in the NT, the office and dignity of the apostles of Christ, apostleship
Part of Speech: noun feminine
Citing in TDNT: 1:446, 67
From G649; commission, that is, (specifically) apostolate: - apostleship.
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 ἀποστολή; click on the second column to search for that grammatical form of the root ἀποστολή; click on the third column to search for that word and grammatical form; click on the total to search for the root ἀποστολή.