Webster’s Revised Unabridged Dictionary · 1913
Proportionable
Pro·por′tion·a·ble (·ȧ·b'l), a. Capable of being proportioned, or made proportional; also, proportional; proportionate. — Pro·por′tion·a·ble·ness, n.
But eloquence may exist without a proportionable degree of wisdom. Burke.
Proportionable, which is no longer much favored, was of our [i. e., English writers'] own coining. Fitzed. Hall.