Definition of brashest:
(adj) :
(of people or behaviour) Overly bold or self-assertive to the point of being insensitive, tactless or impudent; shameless.
(adj) :
(of actions) Overly bold, impetuous or rash.
(adj) :
(of things) Bold, bright or showy, often in a tasteless way.
(n) :
A rash or eruption; a sudden or transient fit of sickness.
(n) :
A sudden burst of rain.
(adj) :
(US, colloquial, dated) Brittle (said e.g. of wood or vegetables).