c.1403, frequentative of
swelten "be faint (especially with heat)," c.1386, from O.E.
sweltan "to die," from P.Gmc.
*swel- (cf. O.S.
sweltan "to die," O.N.
svelta "to put to death, starve," Goth.
sviltan "to die"), originally "to burn slowly," hence "to be overcome with heat or fever;" also the source of O.E.
swelan "to burn," from PIE base
*swel- "to shine, burn" (see
Selene). For specialization of words meaning "to die," cf.
starve.