Lexicographical Interdependence

Day 1: one-syllable words;
Day 2: two-letter words;
Day 3: three-letter words;
Day 4: what could this mean?

Spotting the pattern, said he,
"I'm looking forward to the later rounds...!"

She replied,
"as if I'm going to keep this up for a month!
They take hours, and aren't that good!
Here are my self-imposed criteria;
I urge you to give it a go!"

"Oh," said he,
"you have to do one with 15-letter words,
that's only halfway!"

"Shut up, David!"
"And how shall I shut up, my lady?"

"Accommodatingly and ventriloquizing!
There are some 15-letter words for you.
Put 'em in your pipe and smoke 'em."
Feeling satisfied with the day's work,
she logged off, and went to relax.

"I feel that there was some halfheartedness there,"
scolded David,
"though with some justifiableness.
On an unrelated note,
have you noticed some objectification
of us quadragenarians?"

"Halfheartedness?!
No - simply a spot of intellectualism,
revolutionising the unbelievability
of disenfranchised characteristics.
However, I applaud you
on your bibliographical accomplishments,
and suggest we undertake some experimentation
to ensure that quadragenarians
achieve lexicographical interdependence!"

"Good grief!"