Thinnest
Thinnest is the superlative degree of thin.
thinnest
The superlative of slim is slimmest.
thinner
The superlative form of "movingly" is "most movingly."
thinner, thinnest
The superlative form of clean is "cleanest".
The superlative form of clean is "cleanest".
The superlative form of ancient is ancientosity
comparative - merrier superlative - merriest
"Poke" is a verb and a noun and, as such, does not have a superlative form.