No definitions found for 'on which occasion'
Perhaps one of these:
oncost,
oncogene,
oniscus,
ohnosecond,
omega, ga,
onaga, ks,
onychosis,
one-sixth,
oncograph,
oengus,
omega centauri,
onaka, sd,
one-sixty-fourth,
onyxis,
onychogalea,
onchocerciasis,
onchocerca volvulus,
onsager,
one-sixteenth,
one-sixtieth,
omniscious,
on occasion,
once again