Weathertight window or door (1, 10) comprising a fixed frame which can be associated with a through opening obtained in a wall, at least a wing movable between a closed position and an open position for selectively closing said opening, and sealing means associated with at least a portion of said fixed frame and/or of said wing and arranged such that, when said wing is in said closed position, said through opening is essentially sealed, a control member being provided integral with said wing to drive the opening/closing of the wing and to selectively operate temporary locking means for holding said wing in said closed position, said window or door (1, 10) also comprising thrust means (8, 8') mounted on said wing and operatively connected to said control member, said thrust means (8, 8') comprising a first sliding element movable along a first sliding direction, vertical in use, for integrally displacing a thrust member between a first position, when said wing is in the closed position, and a second position, wherein cooperates with abutment means disposed on said fixed frame to provide the wing with an opening thrust for spacing said wing from said fixed frame, wherein said thrust member of said thrust means (8, 8') is formed of a rigid pin operatively connected to said first sliding element by means of transmission means to be movable along a second sliding direction inclined with respect to said first sliding direction between said first position, wherein said thrust pin is essentially retracted in a housing provided on said wing, and said second position, wherein said thrust pin extracted from said housing and abuts against said abutment means, characterized in that said transmission means comprise a flexible but substantially axially rigid body, associated with a first end portion to said sliding element and with an opposite end portion to said thrust pin, said transmission means being adapted to slide in a shaped guide arranged in said housing and configured to deviate the sliding direction of said thrust pin with respect to the sliding direction of said sliding element. said window or door (1, 10) also comprising thrust means (8, 8') mounted on said wing and operatively connected to said control member, said thrust means (8, 8') comprising a first sliding element movable along a first sliding direction, vertical in use, for integrally displacing a thrust member between a first position, when said wing is in the closed position, and a second position, wherein cooperates with abutment means disposed on said fixed frame to provide the wing with an opening thrust for spacing said wing from said fixed frame, wherein said thrust member of said thrust means (8, 8') is formed of a rigid pin operatively connected to said first sliding element by means of transmission means to be movable along a second sliding direction inclined with respect to said first sliding direction between said first position, wherein said thrust pin is essentially retracted in a housing provided on said wing, and said second position, wherein said thrust pin extracted from said housing and abuts against said abutment means, characterized in that said transmission means comprise a flexible but substantially axially rigid body, associated with a first end portion to said sliding element and with an opposite end portion to said thrust pin, said transmission means being adapted to slide in a shaped guide arranged in said housing and configured to deviate the sliding direction of said thrust pin with respect to the sliding direction of said sliding element.