generosity; tolerance; leniency
Almost always used in the set phrase 大目に見る (to overlook, to be lenient about). The noun/adjectival noun use outside this phrase is rare.
See also: 大目に見る (おおめにみる)
large eyes
Rare literal meaning; not used in modern everyday Japanese. The common word for 'large eyes' is 大きな目.
I'll overlook his mistake this time.
Parents sometimes turn a blind eye to their children's small lies.
In old texts, there are examples where 大目 literally means large eyes.
Compound of 大 (big, great) and 目 (eye). The 'tolerance' sense likely developed from the idea of 'looking at something with big (generous) eyes', i.e., overlooking faults.