تَرَادُفٌ

is synonym with تَتَابُعٌ. (T, S, O.) You say, تَرَادَفَا They followed each other. (K.) And ترادف القَوْمُ The people, or party, followed one another: and in like manner one says of anything following another thing. (Msb.) [See also 4.] And ترادف الشَّىْءُ The thing was, or became, consecutive in its parts; one part of the thing followed another. (M.)

It is also a word alluding to a certain foul act: (M, O:) from الرِّدْفُ signifying العَجُزُ. (M.) You say, (of two boys, or young men, TK,) تَرَادَفَا meaning تَنَاكَحَا. (K.)

And تَرَادَفُوا عَلَيْهِ They aided, helped, or assisted, one another against him. (As, S.) And تَرَادَفَا They aided, helped, or assisted, each other; (O, K;) as also ترافدا. (O.)

As a conventional term in lexicology, تَرَادُفٌ signifies Synonymousness; or the being synonymous. (Mz, 27th نوع; and Kull p. 130.) [You say, of two words, يَتَرَادَفَانِ They are synonymous. See also 3: and see مُتَرَادِفٌ.]