I am grateful to all of you who have objected to having met Sunday. This really reminded me of how little I know of English English... I would have expected it acceptable as a parallel construction to "we met yesterday." Terse, yes, but at least serviceable here in the US.
On the official web page of the American Embassy in Italy mr John Kerry, Secretary of State, says "And the President decided – I got a call Friday night, we met Saturday morning, and the President decided that he ...". Just observing. My mother tongue is not English but I guess it is for John Kerry.
Well, they can overlap in meaning, but there are some differences. You would use "ci siamo conosciute" if you have met someone for the first time. Besides, it implies you got to know each other at some minimum level, at least your names. If you say "ci siamo incontrate", you're not necessarily talking about someone you didn't know before. It could be that you and a friend just happened to be at the same place and quickly greeted.
I think "ci" is actually a "reciprocal pronoun." "The plural reflexive pronouns, "ci "vi," "si" are combined with the first, second or third person plural verb to show reciprocal action-here "we met each other." Reciprocal pronouns show two-way action. Another example, "Si parlano al telefono"--"They talk to each other on the telephone."
-iamo is just the verb ending for the first person plural. Ci can be a frustrating word because the rules are a little messy. Observe the following: noi beviamo il caffè, noi andiamo via, noi lo mangiamo stasera. None of these actually require ci or ce, but it can be used to strengthen or alter the meaning of the sentence: noi ci beviamo il caffè, noi ce ne andiamo via, noi ce lo mangiamo stasera.
For this sentence in particular, ci is necessary because there has to be a way to express who met who. For example, "le abbiamo conosciute domenica" = we met them Sunday. You don't want that kind of confusion! Here, the verb is actually conoscersi conoscere + reflexive pronoun. There are other verbs that can be reflexive (or not):
- Sentirsi: mi sento stanco/I feel tired
- Sentire: sento qualcosa/I hear something
- Chiamarsi: mi chiamo Dario/my name is Dario/I am called Dario
- Chiamare: chiamate la polizia!/call the police!
- Vestirsi: perché non ti vesti?/why don't you get dressed?
- Vestire: la ragazza veste il suo cane/the girl dresses up her dog
Reflexive verbs require "essere" and the past participle has to agree in number and gender.
Ci siamo conosciute = We met each other (a group of girls or women).
Ci siamo conosciuti = We met each other (a group of men or a mixed group).
Abbiamo conosciuto la ragazza. = We met the girl. . (NOT reflexive).
Conoscevamo la ragazza = We knew the girl. (imperfect tense; not covered yet).
The reflexive pronouns imply that you are doing an action to yourself or that the action implies reciprocity. The first, you can think of verbs like regret, it doesn't require an object, you can't regret someone. You feel regret. The latter take this sentence as an example. You need the reflexive pronoun to indicate that the action is between you two, otherwise the sentence would mean that you both met someone else. Syntactically it is also used to indicate the direct object, much like the dative case in German. "Hanno ti conosciuto" - Here the subject is loro, the verb is conoscere and the object is ti, dative for tu.