for the sake of argument Definition

argument
noun

1. A quarrel or unfriendly discussion.

Thesaurus: disagreement, spat, fight, dispute, quarrel, words, row.
2. A reason for or against an idea, etc.

Thesaurus: evidence, reason, proof.
3. The use of reason in making decisions.
4. A summary of the theme or subject of a book, etc.

Idiom: for argument's sake (for the sake of argument)

Said in order to dismiss less important details so that the main issue or issues can be dealt with.
Example: For the sake of argument, let's say I got the time of the meeting wrong

Etymology: 14c: from Latin argumentum, from arguere to prove.