Old English *swelgan* — A Strong Verb That Weakened
The verb *to swallow* descends from Old English *swelgan*, a strong verb of Class III — the same ablaut class as *drincan* (drink), *singan* (sing), and *swimman* (swim). In Old English, the verb inflected with full vowel gradation: *swelgan* (infinitive), *swealg* (past singular), *swulgon* (past plural), *geswolgen* (past participle). This is the same pattern that gives us the modern alternation drink/drank/drunk.
The Old English forms were regular and alive. A speaker of late Old English would say *he swealg þæt wæter* — he swallowed the water — with the strong past form as naturally as *he dranc þæt win*.
The Loss of Ablaut — Strong to Weak
Something happened in the transition from Middle to Early Modern English: *swelgan* abandoned its strong conjugation. The old ablaut series *swelgan/swealg/swulgon* was replaced by the regular weak pattern *swallow/swallowed*. The strong forms were lost.
This regularisation was not unusual. English shed a large proportion of its strong verbs over the medieval period — *meltan* (melt), *helpan* (help) all followed the same path. Children hearing the language in a mixed environment defaulted to the productive -ed ending, and the old ablaut forms were forgotten.
The root comes from Proto-Germanic *\*swelganą*, reconstructed from the cognates: Old Saxon *farswelgan*, Old High German *swelgan*, Old Norse *svelga*.
German *schwelgen* — Gulping Becomes Revelling
The most striking development in the cognate family is the German reflex. Modern German *schwelgen* does not mean to swallow. It means to revel, to indulge, to wallow in pleasure — *in Erinnerungen schwelgen* means to bask in memories, *in Luxus schwelgen* means to live luxuriously. The physical act of gulping food has been entirely sublimated into a metaphor of sensory excess.
The Proto-Germanic root denoted voracious consumption — the gullet drawing down, taking in greedily. From greedy consumption of food, the meaning extended to greedy consumption of experience, pleasure, sensation. German preserved and intensified this extension while discarding the literal meaning. English went the other direction: *swallow* remained firmly physical and literal.
Dutch has *zwelgen*, retaining the sense of gulping or devouring, confirming the Proto-Germanic form was in circulation with its original meaning before the German semantic drift.
Two Swallows — A Spelling Convergence
English contains two entirely unrelated words spelled *swallow*. The bird — the swift migratory swallow of barns and eaves, *Hirundo rustica* — comes from Old English *swealwe*, from Proto-Germanic *\*swalwōn*. The animal name and the verb share no ancestry whatsoever.
The convergence happened through regular sound change operating on both words independently. Old English *swelgan* shifted through Middle English toward *swolwe*, *swalowe*, eventually settling as *swallow*. Old English *swealwe* (the bird) underwent its own changes along a parallel path and arrived at the same spelling. Two words, two lineages, one form.
Jacob Grimm's method — systematic comparison of cognate forms across languages — is what allows us to untangle this. The German cognate for the bird is *Schwalbe*, for the verb *schwelgen*: two clearly distinct words in German, one word in English.
Survival
The verb *swallow* is one of the core verbs of the Old English inheritance. It did not yield to French synonyms in the Norman period. *Swallow* remained the default term and extended naturally into metaphor: to swallow an insult, to swallow one's pride, to swallow a story whole. The metaphorical sense — to accept without resistance — mirrors the physical one with characteristic Germanic directness.