Stressful means causing worry and strain. A stressful job, stressful conditions, deeply stressful.
It describes the cause, and stressed describes the person. Stressful and stressed are the same -ful and -ed pattern as painful and pained. Note stress, which in physics and engineering means force per unit area and in language means emphasis on a syllable — three quite separate technical meanings for one word; and that workplace stress is a recognised health and safety matter with employer duties attached.
1adjectivestressfulCausing worry and strain.
“It was a stressful nine months and it is over.”
synonyms: taxing, demanding
stressful is a quality of causing strain.
Latin
distringō
Old French
destrecier
Middle English
destresse
English
stress
English, today
stressful
From stress + -ful. stress comes from Middle English destresse, from Old French destrecier, from Latin distringō. From a shortening of Middle English destresse, borrowed from Old French destrecier, from Latin distringō (“to stretch out”). This form probably coalesced with Middle English stresse, from Old French estrece (“narrowness”), from Vulgar Latin strictia, from Latin strictus (“narrow”). Displaced native Old English swēġ (“accent, stress”), though strictly in the grammatical sense. In the sense of "mental strain" or “disruption”, used occasionally in the 1920s and 1930s by psychologists, including Walter Cannon (1934); in “biological threat”, used by endocrinologist Hans Selye, by metaphor with stress in physics (force on an object) in the 1930s, and popularized by same in the 1950s.
Etymology from Wiktionary, CC BY-SA