tutear

(transitive) to address someone informally with tú, rather than the formal usted or the informal pronoun vos used in certain countries; to thou 2017 November 25, Jaime Rodríguez, “Vallejo y Varane, los 'chicos formales' [Vallejo and Varane, the "formal boys"]”, in El Mundo[1]: […] se dio la vuelta para estrechar la mano de su guardaespaldas: «Gracias por acompañarme». El central no gasta tatuajes ni peinados atrevidos. Cursa estudios de INEF en la Universidad de Zaragoza, se acordó de su novia en el discurso de presentación en el Bernabéu y hay que insistirle para que rompa a tutear. […] he turned to give his bodyguard a handshake: "Thank you for accompanying me". The central defender doesn't wear tattoos or bold haircuts. He studies Exercise and Sport Sciences at the University of Zaragoza, he remembered [to thank] his girlfriend at his introductory speech at Bernabéu, and you have to insist that he start using tú.