From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): of Swell

(2): p. p. of Swell.

(3): ( a.) Enlarged by swelling; immoderately increased; as, swollen eyes; swollen streams.

International Standard Bible Encyclopedia [2]

swōl ´' n ( πίμπασθαι , pı́mprasthai , only in   Acts 28:6 ): The Melitans expected to see Paul poisoned by the viper's bite. the Revised Version (British and American) and the King James Version translate it "swollen," but the word is used by certain medical writers in the sense of inflammation; see Nicander, Theriaca , 306; Hesiod, Theogonia , 856, expressing thereby the burning up by a thunderbolt. Swelling accompanies the local lesion of snake-bite and often large purpuric exudation of blood, as well as paralysis, especially of the lower limbs.