What condition is characterized by split or brittle nails?

Onychorrhexis is indeed characterized by split or brittle nails. This condition is marked by longitudinal ridges or splits in the nail plate, resulting in a fragile texture. It can be caused by factors such as excessive nail trimming, harsh chemical exposure, or underlying health issues.

The other conditions mentioned function differently: plicatured nails refer to nails that form a "folded" or "bent" appearance, often due to improper growth or injury. Agnail, or hangnail, refers to a small piece of skin that hangs loose near the nail but doesn't directly involve the nail's structure itself. Beau's lines are transverse grooves or indentations on the nail surface that typically indicate a temporary interruption in nail growth usually due to systemic illness or trauma. Understanding these distinctions helps in recognizing specific nail conditions and applying the correct treatments.