disadvantage;  handicap
To be at a disadvantage compared with somebody
To be put at the greatest disadvantage
This new law will put unmarried couples at a disadvantage;  This new law will be unfair to unmarried couples;  This new law will disadvantage/penalize unmarried couples
He favoured his children over his wife in his will
He was handicapped by not being able to speak English
disadvantageous;  unfavourable
It is very disadvantageous/unfavourable to small and medium-sized businesses