Tense exchanges occur when the past and present tenses of the same verb lock on to, or interlock with, another letter or letters to make two other words. Thus FALL and FELL appear in FALLOW and FELLOW, locked on to -OW; RUN and RAN appear in RUIN and RAIN, interlocked with -I. The tenses always appear in the same position(s) in the two words.
Word Ways: Vol. 42
, Article 10.
Available at: http://digitalcommons.butler.edu/wordways/vol42/iss1/10