1) such a one, a certain one, i.e. one whose name I cannot call on the instant, or whose name it is of no importance to mention
Part of Speech: noun masculine or feminine or neuter
Probably from the same as G1171 (through the idea of forgetting the name as fearful, that is, strange); so and so (when the person is not specified): - such a man.
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 δεῖνα; click on the second column to search for that grammatical form of the root δεῖνα; click on the third column to search for that word and grammatical form; click on the total to search for the root δεῖνα.