Past Tense of “swell”
The past tense of swell is swelled; the past participle is swollen.
Why “swell” behaves this way
"Swell" comes from Old English "swellan," a Class III strong verb whose participle "swollen" preserves the older ablaut vowel and the strong-verb "-en" ending, even though the simple past "swelled" has become a regular-looking "-ed" form rather than keeping a distinct vowel-shifted past tense of its own. This puts "swell" in the same mixed-pattern category as "sow/sowed/sown" and "show/showed/shown" — a regular simple past paired with a genuinely archaic-feeling strong participle.
"Swollen" is used specifically for physical swelling — a swollen ankle, swollen eyes, a swollen river — while the figurative and abstract senses (swelling pride, swelling numbers, swelling music) increasingly favor the regular participle "swelled" instead, a genuine and fairly clean semantic split that most native speakers apply intuitively without being taught it explicitly. This kind of sense-based split between two competing participles is relatively unusual in English, sharing more in common with the "hanged"/"hung" distinction (where the meaning, not the region, determines the correct form) than with the purely regional "smelled"/"smelt" pattern.
The common confusion
The main confusion is choosing between "swollen" and "swelled" as the participle: "her ankle has swollen to twice its size" sounds correct for the physical sense, while "the crowd had swelled to thousands" sounds correct for the figurative sense, and mixing the two up — "the crowd had swollen" or "her ankle has swelled" — sounds subtly off to most native speakers even though grammar references don't always spell out the distinction clearly. A separate confusion involves the noun "swelling" (an inflamed area of the body), which some writers mistakenly treat as though it must relate only to the physical sense, when the underlying verb it derives from covers the full range of both literal and figurative meanings.
How it's actually used
"Swell" also survives as a somewhat dated American slang adjective meaning "excellent" or "wonderful" ("that's just swell"), a usage now strongly associated with mid-twentieth-century American English and used today mostly for deliberate period flavor or gentle irony rather than as sincere, contemporary praise. In music, "swell" also functions as a technical noun describing a gradual increase in volume, and in ocean navigation it describes a series of long, rolling waves, both nominal senses that share the verb's core underlying image of a gradual, building increase.
Across the tense system
The passive voice appears constantly with the physical sense — "his hand was swollen after the fall" — while the figurative senses more often appear in the active voice with an inanimate subject doing the swelling ("the orchestra swelled to a triumphant finale"), a pattern that mirrors the same literal-versus-figurative split seen in the choice between "swollen" and "swelled." The progressive "swelling" is common in both senses to describe an action still in progress — "the crowd is swelling by the minute," "her ankle is swelling badly" — before the process reaches its completed, described state.
Common real mistakes
The most common error is using "swelled" where the physical sense specifically calls for "swollen" ("his ankle has swelled" instead of the more natural "has swollen"), or the reverse, using "swollen" for a purely figurative or musical sense where "swelled" reads more naturally. A less common slip is the invented blend "swellen," which no dictionary recognizes. Medical writing translated from other languages shows a third problem: using "swelled" inconsistently alongside "swollen" within the same clinical document describing a single patient's symptoms, an inconsistency that can read as sloppy even though both forms are independently correct in their own contexts. A fourth error is misapplying the dated slang adjective "swell" as if it needed a past-tense form of its own, when it functions purely as an unchanging adjective rather than a conjugated verb.
Examples
- Her ankle had swollen to twice its normal size by evening.
- The crowd swelled to thousands before the concert began.
- The music swelled dramatically during the final scene.
- His pride swelled as he watched his daughter graduate.
- The river had swollen well beyond its banks after the storm.
- Membership has swelled significantly since the new policy took effect.
Memory trick
Split it by domain: reach for "swollen" when a body part or a river is physically bigger than usual, and reach for "swelled" for anything figurative — pride, crowds, music, numbers. The physical sense keeps the old-fashioned "-en" ending; the abstract sense has mostly moved on, one of the cleaner sense-based splits on this entire list.