There are multiple definitions - click on the translation that matches your context.

acción reconvencional

full

counterclaim

noun

Comparative law notes

Spain

civ.,buyer’s action to cancel a sale due to hidden/latent defects in the goods sold

Definitions of counterclaim

English

a claim filed by a defendant against a claimant in a civil action

Stevens filed a counterclaim stating that the claimant owed him money for unpaid orders.