What condition is characterized by split or brittle nails with lengthwise ridges and a rough appearance?

The condition characterized by split or brittle nails that exhibit lengthwise ridges and a rough texture is known as onychorrhexis. This condition typically arises due to various factors such as trauma, overexposure to water or chemicals, or underlying health issues. The presence of lengthwise ridges indicates a disruption in the normal formation of the nail plate, which can contribute to its brittleness and propensity to split.

In contrast, onychotoxis refers to a specific condition where the nails appear affected by environmental factors, and it does not specifically describe the rough appearance or ridging. Plicatured nails are characterized by a fold or bending of the nail plate but do not necessarily imply brittleness or ridging. Onychophagy is the medical term for nail biting, which involves damage to the nails but does not match the description of split, brittle nails with ridges. Thus, onychorrhexis is the term that accurately describes the symptoms presented in the question.