Swell, a verb that implies increase or improvement, has several synonyms that can be used in various contexts. Among them, expand, enlarge, and rise suggest growth or expansion in size or volume. Meanwhile, surge, soar, and escalate imply an increase in intensity, energy, or speed. Other synonyms include bulge, distend, and puff up, all of which suggest an uneven or irregular increase in volume. Additionally, prosper and flourish suggest a positive development or success, while peak and climax denote a culminating point or pinnacle. All in all, using synonyms for swell can help to add variety and nuance to one's writing or speech.