confestim

Analyzable as con- +‎ *fes +‎ -tim, built on the same root as the verb festīnō (“to hasten”). De Vaan, citing Schrijver, identifies the root as *bʰris-, alleged to also be the source of Welsh brys (“speed, haste”). If this etymology is correct, the Latin form developed a syllabic resonant (*-r〭-) which was then replaced with *-er-, and the resulting cluster *-rst- was then regularly simplified to -st- (compare testis). The ending comes from the adverbial accusative of a deverbal noun, which De Vaan reconstructs as Proto-Indo-European *bʰristi-, Proto-Italic *fristi- (“haste”).^[1]

• (Classical Latin) IPA^(key): /konˈfes.tim/, [kõːˈfɛs̠t̪ɪ̃ˑ]
• (modern Italianate Ecclesiastical) IPA^(key): /konˈfes.tim/, [koɱˈfɛst̪im]
• Per Bennett (1907)^[2] Marx considered this word to have a long ē by analogy with manifēstus, although the presence of a long vowel in the latter word is also uncertain.

cōnfestim (not comparable)

1. immediately, forthwith

   Synonyms: statim, extemplō, continuō, īlicō, repente, raptim, breviter, protinus

   • c. 69 CE – 122 CE, Suetonius, De vita Caesarum 2 10:

     Omnium bellōrum initium et causam hinc sūmpsit: nihil convenientius dūcēns quam necem avunculī vindicāre tuērīque ācta, cōnfestim ut Apollōniā rediit, Brūtum Cassiumque et vī necopīnantīs et, quia prōvīsum perīcu­lum subterfūgerant, lēgibus adgredī reōsque caedis absentīs dēferre statuit.

     The source and cause of all the wars he took from this: holding nothing more fitting than to avenge his uncle and maintain the validity of his enactments, immediately on returning from Apollonia he resolved to take the unexpecting Brutus and Cassius by force as well as to resort to laws and prosecute them for murder in their absence, as they had fled the foreseen danger.

• “confestim”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press
• “confestim”, in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers
• confestim in Gaffiot, Félix (1934) Dictionnaire illustré latin-français, Hachette.