Some ropes are joined by an 'air splice' which is a blast of air to entangle fibers from the bitter end of one yarn (strand) to the bitter end of another. This can create a strong union, but it comes along with slightly increased diameter at the air splice.
Ropeshield, with all due respect, if you were to nick a single strand of a 24 strand rope, you'd have one point at which the fibers were not joined. If you pull that apart and try to piece in a 'repair', you'll end up with two points at which the strand is compromised.
Not all rope construction is the same, as everyone has mentioned here, but if you're referring to our typical climbing lines (and you left your air splicing machine at home), it may be best to leave things alone. Make the decision: use it, cut it, or 'recycle' it for some other purpose.