principal

(noun) the original amount of a debt on which interest is calculated.

(noun) the educator who has executive authority for a school. Synonyms: school principal, head teacher, head. Examples: "She sent unruly pupils to see the principal."

(noun) an actor who plays a principal role. Synonyms: star, lead.

(noun) capital as contrasted with the income derived from it. Synonyms: corpus, principal sum.

(noun) (criminal law) any person involved in a criminal offense, regardless of whether the person profits from such involvement.

(noun) the major party to a financial transaction at a stock exchange; buys and sells for his own account. Synonyms: dealer.

(adj) most important element. Synonyms: chief(prenominal), main(prenominal), primary(prenominal), principal(prenominal), master(prenominal). Examples: "The chief aim of living." "The main doors were of solid glass." "The principal rivers of america." "The principal example." "Policemen were primary targets." "The master bedroom." "A master switch."