American Dictionary of the English Language

DISADVANTAGE, noun

1. That which prevents success, or renders it difficult; a state not favorable to successful operation. The army commenced an attack on the enemy, notwithstanding the disadvantage of its position.

2. Any unfavorable state; a state in which some loss or injury may be sustained. Hence,

3. Loss; injury; prejudice to interest, fame, credit, profit, or other good; as, to sell goods to disadvantage

DISADVANTAGE, verb transitive To injure in interest; to prejudice.