Definition of rootfast in English:

rootfast

adjective

rare, archaic, poetic
  • Firmly held by the roots. Frequently (and in earliest use) figurative: securely established; firmly fixed.

Origin

Old English; earliest use found in The Anglo-Saxon Chronicle. From root + fast. Originally perhaps after early Scandinavian, although compare earthfast. In later use apparently re-formed in the 19th cent.

Pronunciation

rootfast

/ˈruːtfɑːst//ˈruːtfast/