noun
reliable person; person of firm character; gutsy person
Describes someone who is dependable, steady, and has a strong, reliable personality. Often used as a compliment.
彼女はしっかり者で、仕事も家事もきちんとこなす。
She is a reliable person who handles both work and housework properly.
あの子は小さいのにしっかり者だね。
That child is so young but has such a firm character, isn't it?
しっかり is an adverb/adjective meaning 'firmly, steadily, reliably'. しっかり者 is a noun derived from it, referring to a person who embodies those qualities.
Compound of しっかり (firmly, steadily) and 者 (person). The exact origin of しっかり is uncertain, but it is a native Japanese mimetic/adverbial word.