As an adjective peakiest
is (peaky).
As a noun peakist is
a supporter of the peak oil theory, or one who advocates policies that depend on this theory.
peakiest
English
Adjective
(head)
(peaky)
peaky
English
Adjective
(er)
Sickly; peaked.
Characterised by peaks.
peakist
English
Noun
(
en noun)
A supporter of the peak oil theory, or one who advocates policies that depend on this theory