Theorist

The′o-rist

,

Noun.

[Cf. F.

théoriste

.]

One who forms theories; one given to theory and speculation; a speculatist.

Cowper.

The greatest

theoretists

have given the preference to such a government as that which obtains in this kingdom.

Addison.

,

Noun.

One who forms theories; one given to theory and speculation.

The greatest theorists have given the preference to such a government as that of this kingdom.

theorist ‎(plural theorists)

Someone who constructs theories, especially in the arts or sciences.
- 2012 January 1, Michael Riordan, “Tackling Infinity”, in American Scientist, volume 100, number 1, page 86:
  Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains.

someone who constructs theories

Persian: تئوریسین (fa) ‎(teorisian)
Polish: teoretyk m, teoretyczka f
Portuguese: teorista m, f, teórico (pt) m
Romanian: teoretician (ro) m, teoreticiană (ro) f
Russian: теоре́тик (ru) m ‎(teorétik)
Serbo-Croatian:

Cyrillic: теоретичар m, теоретичарка f

Roman: teoretičar (sh) m, teoretičarka (sh) f
Spanish: teórico (es) m, teórica (es) f
Swedish: teoretiker (sv) c