A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

in and out • ins and outs
in and out—
1
. said of smb. coming and going from a place
all the time: Sam was in and out of the office most of the day
today. 2. (of work, etc.) not continuous; done at irregular inter-
vals: His engagements are only for particular plays —“in and
out” work.
ins and outs —
1
. the details or fine points of smth.: She left
the explanation to those who pretended to understand the ins
and outs of the gravest mysteries of life. 2. people holding
office and those out of office or in opposition: In Britain the
parties are organized under party chiefs, and elections are sim-
ply a struggle between the ins and the outs.
See also: inside and out / inside out.
in another world • on other worlds
in another world —
1
. out of touch with reality; unaware of
the latest news, etc.: I had for some time been living, as it
were, in another world. I now came down to earth with a
bang. 2. is used of a state of existence after death: A night’s
reflection has convinced me that there is no hell for these
women in another world. Cf.: in this world — during our life
on earth (as distinguished from the world beyond the grave): All
human beings are destined to exist forever — in this world,
and the world to come.
Note: 
The expression does not correlate in meaning with the
phrase there’s a whole other world out there— there is a whole
new world of ideas, information, etc. that is different from what
we know: There’s a whole other world out there, one in which
chemists work on more immediate problems in close collab-
oration with customers.
on other worlds —on other planets: Most scientists believe
the universe is so vast that it is almost a statistical certainty
that intelligence exists on other worlds.
See also: in the next world / in the second world.