Repentino vs. súbito vs. brusco

The Spanish words 'repentino', 'súbito', and 'brusco' can all be translated as 'sudden', but each holds a slightly different connotation. While all three refer to the rapid onset, the nuance of each word relies on the type of situation or event they are describing.

Repentino

'Repentino' signifies a sudden or unexpected change or event, something that has rapidly and abruptly come about, typically causing surprise.
Su muerte fue muy repentina.
(His death was very sudden.)
Un repentino cambio de planes nos impidió ir.
(A sudden change of plans prevented us from going.)

Súbito

'Súbito' also refers to an abrupt occurrence, but is often more formal than 'repentino'. It implies immediacy and a lack of warning.
Sufrió un súbito ataque al corazón.
(He suffered a sudden heart attack.)
Esta mañana, hubo un súbito aumento de la temperatura.
(This morning, there was a sudden rise in temperature.)

Brusco

'Brusco' describes a jarring or harsh suddenness. It can suggest violence or significant shift and is often used to refer physical movements or changes in direction, or dramatic shifts in situations.
El autobús hizo un giro brusco.
(The bus made a sudden turn.)
Hubo un brusco descenso en las ventas.
(There was a sharp drop in sales.)

Summary

'Repentino', 'súbito', and 'brusco' each capture differing senses of the concept of suddenness. 'Repentino' denotes unexpectedness and surprise, 'súbito' emphasizes immediacy and lack of warning, while 'brusco' portrays harshness or an abrupt change, typically related to physical movements or dramatic shifts.