Definition of retrorse in English:

retrorse

adjective

Biology
  • Turned or pointing backward.

    ‘retrorse spines’
    • ‘In fish, the retrorse (backward) inclination of the myomeres forms a precursor of the differentiation between a deep and a superficial musculature of the trunk.’
    • ‘As the bee's proboscis is inserted into the flower it pushes past the retrorse anthers to the nectar at the base of the tube.’

Origin

Early 19th century: from Latin retrorsus, contraction of retroversus, from retro backward + versus turned (past participle of vertere).

Pronunciation:

retrorse

/rəˈtrôrs/