i-adjective
heartening; reassuring
Describes a feeling of emotional support or confidence from someone's presence, words, or a situation.
君がいてくれると心強いよ。
It's reassuring to have you here.
彼の言葉はとても心強かった。
His words were very heartening.
Antonym; means 'lonely', 'helpless', or 'forlorn', expressing a lack of emotional support.
Compound of 心 (こころ, 'heart, mind') + 強い (つよい, 'strong'). The reading づよい is a rendaku form of つよい.