This is the 5922nd most frequent Spanish word.
umbral
Threshold.
Physical boundary or technical hardware of the object.
Cruzó el umbral de la puerta con seguridad.
He crossed the threshold of the door confidently.
Figurative boundary, denoting beginnings or changes.
Está en el umbral de un gran descubrimiento.
He is on the threshold of a great discovery.
Limit or maximum level of toleration.