second person: pronouns and verbs used to refer to the person addressed by the language in which they occur
person: a grammatical category used in the classification of pronouns, possessive determiners, and verb forms according to whether they indicate the speaker, the addressee, or a third party
muon: an elementary particle with a negative charge and a half-life of 2 microsecond; decays to electron and neutrino and antineutrino