a surname

any choices, arbitrary selections / free will

arbitrary, as one wants or thinks / free, up to a person, according to their will, voluntary

tenure, term or period of office

(programming) nil

(biochemistry) serotonin

(grammar) second person

two persons / a couple, pair

popularity

(dated) one's family, (especially) one's wife / household; family and servants living within a house / (dated) household servants; retainers living in or frequently entering a noble family's house