Which condition is characterized by thickened and overgrown nails?

Onychauxis is indeed characterized by thickened and overgrown nails. This condition involves an increase in the thickness of the nail plate, which often results in nails that can appear bulky or distorted. It can arise for various reasons, including trauma, persistent pressure, or certain systemic health issues.

In contrast, onychomycosis refers to a fungal infection of the nails that can cause discoloration and possible thickening, but it is not solely characterized by thickening. Onycholysis involves the separation of the nail from the nail bed, typically not affecting the thickness of the nail itself. Paronychia is an infection of the skin around the nails and will not lead to the thickening of the nails but can cause redness and swelling around them.