ud
/ˈud/ · B1 · pron
usted
Ud. = short for usted, from vuestra merced (your grace)
Ud. is the written abbreviation of usted, the formal 'you'. Usted grew out of vuestra merced, 'your grace', and that is why it takes third-person verbs: Ud. habla. The older spelling Vd. still shows the v of vuestra.