Conjugation

itessereirregular

group: -ere · participle: stato · aux. essere

Unlike French, Italian builds the past of essere with essere itself (sono stato), and borrows the participle stato from stare; sono is both 'I am' and 'they are'.

esserirregular

group: -er · participle: sido · aux. haber

A patchwork of two Latin verbs: the present (soy, eres, es), imperfect (era) and preterite (fui) continue ESSE, but the infinitive ser, the subjunctive sea and the participle sido come from SEDĒRE 'to sit'.

frêtreirregular

group: 3rd group · participle: été · aux. avoir

être takes avoir in the passé composé (j'ai été); its participle été and its imperfect j'étais were borrowed from STĀRE (STATUM, STĀBAM), the verb that became Spanish estar.

ptserirregular

group: -er · participle: sido · aux. ter

Like Spanish, a blend of ESSE (sou, é, era, foi) and SEDĒRE (ser, seja, sido), with the preterite fui shared with ir; Brazil says você é, vocês são with the 3rd-person forms.

rofiirregular

group: -i · participle: fost · aux. avea

fi is traditionally derived from FIERI 'to become'; the present sunt, este and the imperfect eram continue ESSE, and 3s este is shortened to e in speech. Romanian has a single 'to be', so fi also covers the estar sense.

caserirregular

group: -er · participle: estat · aux. haver

Also written ésser in formal style; the participle estat is shared with estar (sigut is also accepted), and the past is built with 'go': vaig ser 'I was'.

SUM, EST, SUNT still echo in soy/es/son, suis/est/sont, sono/è/sono, sou/é/são, sunt/este/sunt and sóc/és/són, and Latin ERAM survives intact as Spanish, Portuguese and Romanian era (Catalan era, Old Italian era, today ero). Most sisters leaned on neighboring verbs to fill the gaps: Spanish and Portuguese on SEDĒRE (ser, sea/seja), French, Italian and Catalan on STĀRE (été, stato, estat), while Romanian fi is traditionally traced to FIERI 'to become'.