noun which may take the genitive case particle 'no', na-adjective
skinny; thin and bony
Describes a person who is very thin, often with a negative or unflattering nuance, suggesting a lack of healthy flesh.
彼は痩せぎすで、いつも体調を崩しやすい。
He is skinny and always prone to getting sick.
痩せぎすな体型を気にしている。
She is self-conscious about her thin and bony figure.
痩せる is the verb 'to lose weight' or 'to be thin', while 痩せぎす is a noun/adjective describing a skinny, bony state.
細い means 'thin' or 'slender' and can be neutral or positive, whereas 痩せぎす often carries a negative, unhealthy connotation.
Compound of 痩せ (yase, 'thinness', from verb 痩せる) and ぎす (gisu, possibly from キス, an old word for 'lean' or 'bony'). The exact derivation of ぎす is uncertain.