The Collaborative International Dictionary
Proportionably
Proportionably \Pro*por"tion*a*bly\, adv.
Proportionally.
--Locke.
Wiktionary
proportionably
adv. In a proportionable manner; proportionately.
Usage examples of "proportionably".
If he imports a slave, he adds one to the number of labourers in his country, and proportionably to it's profits & abilities to pay taxes.