We don't have synonyms for serjeanty yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sergeant, serjeant and serjeantry.
(n) :
(law, historical) A land tenure in which a tenant provided his liege with some kind of personal service, as opposed to nonpersonal service, such as paying tax (socage)
(n) :
(law, historical) A land tenure in which a tenant provided his liege with some kind of personal service, as opposed to nonpersonal service, such as paying tax (socage)