An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A slowing down, holding back, or hindrance,

M.E., from M.Fr., from L retardare "to make slow, delay, keep back, hinder," from → re-, intensive prefix, + tardare "to slow."

Dirkard "delay," from dir "slowly, tardily; late" (Mid.Pers. dêr, variants dagr, drâz "long;" (Mod.Pers. derâz "long," variant Laki, Kurdi derež); O.Pers. darga- "long;" Av. darəga-, darəγa- "long," drājištəm "longest;" cf. Skt. dirghá- "long (in space and time);" L. longus "long;" Gk. dolikhos "elongated;" O.H.G., Ger. lang; Goth. laggs "long;" PIE base *dlonghos- "long") + kard past stem of kardan "to do, to make" (kâr "work," varaint kar (Mid.Pers. kardan; O.Pers./Av. kar- "to do, make, build;" Av. kərənaoiti "he makes;" cf. Skt. kr- "to do, to make," krnoti "he makes, he does," karoti "he makes, he does," karma "act, deed;" PIE base k^wer- "to do, to make").

The act of retarding or state of being retarded. → retardation plate.

Verbal noun of → retard.

Same as → wave plate.

→ retardation; → plate.

The electric or magnetic field that is derived from the → retarded potentials.

Retarded, adj. of → retard; → field.

The → electromagnetic potential at an instant in time and a point in space as a function of the charges and currents that existed at earlier times.

Retarded, adj. of → retard; → potential.

An ordinary electromagnetic wave that goes forward with time. → Maxwell's equations are indifferent to the distinction between past and future. It is therefore permissible for the electromagnetic waves to go backward in time. Forward-in-time waves are called retarded, as they arrive after they are sent by the transmitter. Backward-in-time waves are called → advanced wave.

Retarded, adj. of → retard; → wavel.