MAGMA, ONION, RESTORE, ENTERTAINMENT, ABRACADABRA etc.
The above list consists of words structured ABA, where A is a sequence of 2 or more letters and B of 1 letter or more.
The concatenations A and B may be meaningless, but the final word must be non-esoteric, appearing in a respectable dictionary.
See how far ( maximal 2A+B) you can go, you will probably manage without my samples, but try to get an uninterrupted (lengthwise) listing of words from 5 letters up.
A different search gave the ones with longest As,
which I found more interesting.
(I omitted uricosuric and some others as esoteric).
For me, UNDERGROUNDER seemed the best.
4 5 4 SINGULARISING
5 3 5 UNDERGROUNDER
4 3 4 ABRACADABRA
4 3 4 TARATANTARA
4 1 4 EINSTEINS
4 1 4 GALENGALE
4 1 4 MUCKAMUCK
4 1 4 OKEYDOKEY
4 1 4 OUTSHOUTS
4 1 4 OVERCOVER
4 1 4 TARANTARA
4 1 4 TRINITRIN