The word amontonó is the preterite form of amontonar in the third person singular.
See the full amontonar conjugation

amontonar

Elisa amontonó una generosa porción de espaguetis en su plato.
Elisa heaped a generous portion of spaghetti onto her plate.
El ladrón amontonó los fajos de billetes en el suelo para contarlos.
The thief piled the bundles of bills on the floor to count them.
Amontonó para un montón de candidatos.
He bundled for a lot of candidates.
Amontonó los periódicos viejos en un contenedor para reciclarlos.
He piled the old newspapers in a container for recycling.
El bibliotecario amontonó unos libros para colocarlos en los estantes.
The librarian piled the books up to placed them on the shelves.
La nieve se amontonó tan alto afuera que solo nos quedamos en casa y jugamos juegos de mesa toda la semana.
The snow piled up so high outside that we just stayed in and played board games all week.
Hacía mucho calor y se acostó a descansar a la sombra de un gran baobab. Amontonó los sombreros a su lado y no tardó en quedarse dormido.
The day was hot, and he rested himself down under the shade of a large baobab. He put the pile of hats next to himself and promptly dozed off.
¿Qué tal si me amontono sobre ti?
That's it. How about I dogpile you?
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