what is it?
Spanish has two main adversative conjunctions that learners often confuse: pero and sino. They are not interchangeable. Pero introduces a contrast or qualification — it adds information that limits or complicates the first clause without cancelling it. Sino introduces a correction — it replaces or contradicts a negated element in the first clause, asserting what is true instead. A third option, no obstante, functions as a formal or literary «nevertheless» and belongs to a different register entirely.
when to use it
Use sino when the first clause contains an explicit negation (no, nunca, jamás, etc.) and the second clause directly replaces or corrects the negated element. The two clauses must refer to the same grammatical slot — the second says what the first denies.
Use sino que — with que — when the correcting element is a finite verb clause (i.e. it has its own conjugated verb). Sino alone can only precede a noun, adjective, adverb, or infinitive.
Use pero in all other cases of contrast or qualification — including after a negation when the second clause does not correct but merely adds a contrasting fact. If the first clause is affirmative, pero is the only option.
Use no obstante in formal written registers as a sentence-initial or clause-initial connector meaning «nevertheless» or «however». It does not replace pero or sino in everyday speech.
Quick test: ask yourself whether the second clause replaces the negated element or merely contrasts with the first clause. Replacement → sino. Contrast → pero.
formation
The structures below summarise how each connector is built into a sentence. The key variable is what follows the connector.
| connector | what follows | example frame |
|---|---|---|
| pero | any clause (affirmative or negative) | … , pero + clause |
| sino | noun / adjective / adverb / infinitive | no … , sino + noun/adj/adv/inf |
| sino que | finite verb clause | no … , sino que + conjugated verb |
| no obstante | full clause (formal register) | No obstante, + clause |
Sino is written as one word. Do not confuse it with si no (two words), which means «if not» and belongs to conditional structures.
examples in context
common pitfalls
Using pero when sino is required. When the second element corrects a negated one, pero is wrong. «*No es antipático, pero tímido» is ungrammatical. The correct form is «No es antipático sino tímido». Pero can only link two full clauses, not replace a negated adjective with another adjective.
Omitting que before a finite verb. «*sino estoy dispuesto a ayudarlo» is incorrect because «estoy» is a conjugated verb. Add que: «sino que estoy dispuesto a ayudarlo». The rule is simple: if what follows sino has its own subject and conjugated verb, que is obligatory.
Using sino outside a negative context. Sino requires a preceding negation. «*Habla francés, sino mal» is wrong because the first clause is affirmative. The correct form is «Habla francés, pero mal». Without a negation in the first clause, pero is the only valid choice.
Three sentences, graded here. Nothing is saved and no account is needed.
El médico no solo le recetó un tratamiento, ___ le explicó con detalle cómo seguirlo.
Fill in the blank with the correct connector to complete the sentence.