1) singleness, simplicity, sincerity, mental honesty
1a) the virtue of one who is free from pretence and hypocrisy
2) not self seeking, openness of heart manifesting itself by generousity
Part of Speech: noun feminine
Citing in TDNT: 1:386, 65
From G573; singleness, that is, (subjectively) sincerity (without dissimulation or self seeking), or (objectively) generosity (copious bestowal): - bountifulness, liberal (-ity), simplicity, singleness.
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 ἁπλότης; click on the second column to search for that grammatical form of the root ἁπλότης; click on the third column to search for that word and grammatical form; click on the total to search for the root ἁπλότης.