Vous avez cherché: once in a while (Anglais - Latin)

in a short while
eo ipso tempore

once in a lifetime
sua

once in life
semel tantum in vita

as in a cave
sicut

in a test-tube
in vitro

in a wide sense
lato sensu

power in a name.
in virtute nominis.

in a word, and deed,
mea culpa

farmer working in a
agricola laborat

lying in a manger;
jacenti in praesepio

and heaven in a crystal
per inoequalem motum respectu totius

one in a certain place,
in quodam loco

connaturaliter in a natural way;
connaturaliter

disposed, in a certain condition
habitus

i'm sitting in a chair
poeta

ovid tells the remarkable sculptor pygmalion was once in cyprus
ovidius narrat olim in cypro sculptorem praeclarum pygmalionem fuisse, qui mulieres prae vitiis multis oderat.

postmodum after a while, later, a little later; afterwards; presently;
postmodum

aliquamdiu for some time, for a considerable time/distance (travel), for a while;
aliquamdiu

and it came to pass after a while, that the brook dried up, because there had been no rain in the land.
post dies autem siccatus est torrens non enim pluerat super terra

and he would not for a while: but afterward he said within himself, though i fear not god, nor regard man;
et nolebat per multum tempus post haec autem dixit intra se et si deum non timeo nec hominem revereo