-itious

1.
a compound suffix occurring in adjectives of Latin origin (adventitious) and with adjectives, formed in Latin or English, associated with nouns ending in -ition (ambitious; expeditious).
Compare -ite2 , -ous.
Origin
< Latin -icius or -īcius (as in adventitious); and < Latin -itiōsusor -ītiōsus (as in ambitious)
British Dictionary definitions for -itious

-itious

suffix
1.
having the nature of; characterized by: nutritious, suppositious
Word Origin
from Latin -icius, -itious