Difference between For all the world • for the world

for all the world—

1. is used to emphasize assertions of likeness:

• She looked for all the world like her twin sister.

2. without the slightest doubt:

• I thought for all the world that the car would plunge headlong down the bank.

3. (emphatic, negat.) on no account; not for the greatest possible reward:

• I am sure I would not do such a thing for all the world.

for the world — = for all the world 3:

• I wouldn’t for the world go into that deserted house at this time of night.