D defs.my
Entry 1 sense Webster, 1913

Principia

/prĭn-sĭp'-ē-ə/ · Prin·cip·i·a · IPA /prɪnsˈɪpiːə/
01 n. pl. First principles; fundamental beginnings; elements; as. Newton's Principia.
  1. 1.
    First principles; fundamental beginnings; elements; as. Newton's Principia.