-esso

(This etymology is missing or incomplete. Please add to it, or discuss it at the Etymology scriptorium.) Identical in form to the archaic future perfects in -āssō, -āssere, etc., attested contemporary with Ennius, viz. amāssis, levāssō, impetrāssere, and iūdicāssit, respectively of amō, levō, impetrō, and iūdicō.^[1][2] Origin cited as not fully explained. Perhaps connected with a kind of prolepsis invoking a counterfactual use of aspect for emphasis.

• (Classical Latin) IPA^(key): /ˈes.soː/,
• (modern Italianate Ecclesiastical) IPA^(key): /ˈes.so/,

-essō (present infinitive -essere, perfect active -essīvī or -essiī or -essī, supine -essītum); third conjugation

1. Forms a small number of intensive verbs from verbs.

   petessō (“I strive eagerly”), from the verb petō (“I aim, seek”).

   facessō (“I do eagerly; I depart”), from the verb I do, make

¹At least one use of the archaic "sigmatic future" and "sigmatic aorist" tenses is attested, which are used by Old Latin writers; most notably Plautus and Terence. The sigmatic future is generally ascribed a future or future perfect meaning, while the sigmatic aorist expresses a possible desire ("might want to"). It is also attested as having a rare sigmatic future passive indicative form ("will have been"), which is not attested in the plural for any verb.