I heard this on CNBC.

Problem:
“Disection” is not a word.

Explanation:
You might wonder how I could hear the misspelling of a word. The answer is that the mispronunciation is common.

Many seem to believe that “bisection” has a counterpart word that is spelled “disection” (and perhaps even that these are interchangeable). This belief is erroneous.

“Bisect” means to cut into two, where “bi” refers to two and “sect” refers to cut.

“Dissection” is the word that the CNBC journalist should have spoken.

“Dissect” means to cut apart, where “sect” (still!) refers to cut and “dis” — NOT “di”! — refers to apart.

I believe that the mispronunciation of “dissection” as “disection” (sic) comes not only from the similarity to “bisection” (and ignorance about roots of words) but also from the fact that “disection” is simpler to say than is “dissection”. This is consistent with my “Devolution toward Simpler” hypothesis about American English.

Solution:
“Dissection”