adjective/su.sjø/
worried; nervous, hesitant
“J’étais alors très occupé à essayer de dévisser un boulon trop serré de mon moteur. J’étais très soucieux car ma panne commençait de m’apparaître comme très grave, et l’eau à boire qui s’épuisait me faisait craindre le pire.” — I was then very busy trying to unscrew a bolt that was too tight on my engine. I was very worried because my breakdown was beginning to appear very serious to me, and the water to drink which was running out made me fear the worst.
From souci + -eux.