anceps (either long or short) in Latin; in fact they are long 60% of the time, while the Greek anceps syllables (the first, fifth, and ninth elements) are long in 80-90% of lines. As in the Greek trimeter, any long or anceps syllable except the last could be replaced with a double short syllable (u u). As in Greek, there was usually (though not always) a caesura (word-break) after the fifth element.

An example of a Latin iambic senarius (from the prologue to Plautus' Aulularia) is the following:
:ne quís mirétur quí sim, paúcis