陡 is primarily used for physical steepness (roads, slopes, stairs). For 'sudden/abrupt,' it appears in the literary expression 陡然 (dǒurán, suddenly). Common compound: 陡峭 (dǒuqiào, steep and precipitous).
memory
The left radical 阝(阜) means hill/mound. The right side 走 means walk. Imagine trying to walk up a hill — it's steep (陡)!
