d Syllabification: (d)Translate d | into French | into German | into Italian | into Spanish Definition of d abbreviation date. (in genealogies) daughter. day(s):orbital period (Mars): 687.0d deceased. deep. [in combination] (in units of measurement) deci-. (in travel timetables) departs. (d.) died (used to indicate a date of death):Barents, Willem (d.1597) divorced. British penny or pence (of predecimal currency):£20 10s 6d[from Latin denarius 'penny'] Chemistry denoting electrons and orbitals possessing two units of angular momentum:d-electrons[d from diffuse, originally applied to lines in atomic spectra] symbol Mathematics diameter. Mathematics denoting a small increment in a given variable:dy/dxd in other Oxford dictionaries Definition of d in the British & World English dictionary