ˈpīˌran noun
( -s )
Etymology: International Scientific Vocabulary pyr- + -an
: either of two parent cyclic compounds C 5 H 6 O that contain five carbon atoms and one oxygen atom in the ring:
a. : the alpha isomer — called also 2H-pyran
b. : the gamma isomer — called also 4H-pyran ; see pyrone ; compare chroman , xanthene