تَزَاعَمَا
1.
They two competed in discoursing of a thing, and differed respecting it: according to Z, it means they talked of, or related,
زَعَمَات, i. e. [mere assertions, or] stories in which no confidence was to be placed. (TA.) Sh says that التَّزَاعُمُ is mostly used in relation to a thing respecting which there is doubt. (TA.)
2.
One says also, تزاعم القَوْمُ, meaning The people, or party, became responsible, one for another: and hence, تزاعموا عَلَى كَذَا
they leagued together, and aided one another, against such a thing. (TA.)