Solo vs soltanto vs solamente?

Question

I was trying to find out how to translate the word "only" and found three separate words. Could someone help me understand when each of these is used and what the differences are between them? Examples would be amazing.

Answer 1

Hope the following extract may help:

• Solo, soltanto and solamente are both adverbs and conjunctions and their use as such is interchangeable.

• As an adverb their meaning would be equivalent to the English adverb "only" (as in solely, merely or exclusively). For example: Parlo solo/soltanto/solamente inglese. I speak only English

• As a conjunction their meaning would be equivalent to the English conjunction "only" and convey an adverse meaning by describing a negative quality to something otherwise positive. For example: La pizza e buona, solo/soltanto/solamente un po' salata. (The pizza is good, only a little salty).

• Solo, in addition to being an adverb and a conjunction is also an adjective and a noun:

• as an adjective it means something similar to "alone" as in "without company". For example: Viaggio sempre solo. I travel always alone. Or this other one: Dopo la partenza della mia fidanzata sono rimasto solo nella stanza. After the departure of my fiancèe I remained alone in the room.
• as a noun (male) it means sole, single, and its meaning is similar to that of the adjective "only" in English (as in "the one"; "the one person"; "the only person"; "the only one" - This is kind of interesting considering that in English "only" does not have a noun function but it uses a noun to approximate its meaning to the equivalent of the Italian noun solo). For example: Credo che tu non sia il solo ad avere questi dubbi. I think that you are not the only one to have these doubts. In music jargon its meaning would be "soloist or solo". For example: Questa e una composizione per solo. This is a composition for (a) soloist/solo.

Recap:

• Solo/Soltanto/Solamente When used as an adverb or as a conjunction they can be interchanged. These three words translate to "only" (adverb and conjunction) in English.
• Solo is also an adjective and a noun. When it functions as an adjective or as a noun its use cannot be interchanged with soltanto/solamente.
• In all three cases (adjective, adverb and conjunction) solo can be translated as only using the corresponding adjective, adverb and conjunction function that the word only has in English. In the case of the noun function it can be translated as "the only one" because only does not have a noun function in the English language.

Answer 2

There is no difference between the adverbs solo, solamente, and soltanto in terms of meaning and usage. The only difference I can think of comes down to a matter of style: if you have already used adverbs ending with -mente in your sentence, then it’s better to choose either solo or soltanto rather than solamente.

The Treccani dictionary says that solo “[s]i alterna a solamente e soltanto (rispetto ai quali è più fam.)” [trad.: “alternates with solamente and soltanto, compared to which is more familiar”] (sub voce “solo”). Actually, I would say that solo is slightly more common, but not limited to a specific register, as you can find it in every kind of texts.

Indeed, solo is more immediate and spontaneous than the other two synonyms:

Quest’auto mi è costata solo diecimila euro! [This car only set me back € 10,000!]

You can also use soltanto and solamente, of course, but, given that it’s a colloquial sentence, solo turns out to be more spontaneous and direct, as it’s shorter.