An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Cause to feel upset, annoyed, or resentful.
2) Commit an illegal act; break a commonly accepted rule or principle (OxfordDictionaries.com).

M.E. offenden, from O.Fr. ofendre "transgress, antagonize," and directly from L. offendere "to hit, strike against," figuratively "to stumble, commit a fault, displease," from assimilated form of ob "in front of against" + -fendere "to strike, push," from PIE root *g^when- "to strike, kill;" cf. Av. -γna- "slaying," → murder.

Âfandidan, from âfand "strife, war," probably from Proto-Iranian *â-fanda-, from prefix *â- + *fanda-, from *fan- "to move;" cf. Yazghulami fin-/fud "to descend, come down," fəndan- "to bring down;" Roshani sifan-, Bartangi sifân- "to rise;" Skt. phan- "to jump" (Cheung 2007).

A person who commits an illegal act; a person or thing that does something wrong or causes problems (OxfordDictionaries.com).

→ offend; → -er.