From a discussion yesterday with Elizabeth Traugott and Melissa Carvell (about linguistics in the comics), Elizabeth saying:
It’s a cycular process
and then pausing in confusion, and correcting cycular to cyclical. (And I of course took notes on the event.)
Cycular is an inadvertent blend, a combination of cyclical and circular, which were in competition with one another as Elizabeth was framing her sentence. The competition was especially acute because the alternatives are so similar to one another phonologically.
A couple more word blends in conversation from the past few years:
Jackstone Merlot (Jackson + Blackstone) (AMZ, 1/30/08)
It’s ledged in there. (lodged + wedged) (Ned Deily, 9/3/09)
In both, the phonological similarity of the competitors facilitates the error.