reg·is·trant /ˈrɛʤəstrənt/
  登記者
  Reg·is·trant n.  One who registers; esp., one who , by virtue of securing an official registration, obtains a certain right or title of possession, as to a trade-mark.
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  registrant
       n : a person who is formally entered (along with others) in a
           register (and who obtains certain rights thereby)