Semantics

nail
Ребёнку нђдо пострќчь нћгти. The baby's nails need trimming.
thumbnail
У менї сломђлся нћготь на большћм пђльце лљвой рукќ. I broke my left thumbnail.
fingernail
Кђтя соскреблђ нћгтем грїзь со столђ. Katya scraped the dirt from the table with her fingernail.
toenail
Мнљ нђ ногу упђл кирпќч, и тепљрь нћготь чернљет. A brick fell on my foot, and now one of my toenails is turning black.
The word нћготь refers to a part of the human body only; the word кћготь "claw, talon" is used to refer to the corresponding part of an animal's body.