What does «testarazo» mean in Spanish?

A blow struck with the head or received on the head.

Examples of use in Spanish: "¡terrible testarazo se dio contra la viga que sobresalía!".

"los ciervos machos se pelean a testarazos por las hembras".
By extension, strong blow, blow of any kind.

Examples of use in Spanish: "del testarazo se rompió un brazo".

"se dio un fuerte testarazo contra la mesa".
In soccer, a header to the ball.

Examples of use in Spanish: "el futbolista metió un testarazo que puso 2-0 el partido".
Stubbornness, inflexibility and obstinacy.