Definition of "flinchless"

The pale, inscrutable determinateness, and flinchless intrepidity of Pierre, now began to domineer upon them; for any social unusualness or greatness is sometimes most impressive in the retrospect.

1852 July, Herman Melville, “Book XXIV. Lucy at the Apostles’.”, in Pierre: Or, The Ambiguities, New York, N.Y.: Harper & Brothers, […], section IV, page 445