At least 44:
antisyzygy
brachydactyly
hydrodynamically
hydrolytically
hydroxytryptamine
hydroxytryptamines
hypabyssally
hyperdactyly
hypernymy
hyperphysically
hypocotyledonary
hypogyny
hyponymy
hypophysectomy
hypsophyllary
karyotypically
mystifyingly
polydactyly
polyembryony
polygyny
polyhydroxy
polyhydroxybutyrate
polyhydroxybutyrates
polyonymy
polyphyletically
polyrhythmically
polysyllabically
polysynaptically
polysynthetically
psychoanalytically
psychodynamically
psychophysically
psychophysiologically
psychophysiology
pyrolytically
symphyseotomy
symphysiotomy
syndactyly
synonymity
synonymously
synonymy
syzygy
xylopyrography
xylotypography