Quenya 

olla

over

olla prep "over" (= beyond, of things passed over, as in "I went over a river" or "they went over the hill") (PE17:65)

olla

preposition. over [beyond]

arta

across, athwart

arta (4) prep. "across, athwart" (LT2:335), perhaps rather olla in Tolkiens later Quenya.

atta

across, over, lying from side to side

atta (ata-) (4) prep. "across, over, lying from side to side" (VT49:32; it is not quite clear whether this is a Quenya word or not)

or

over

or prep. "over" (CO); in early "Qenya", this preposition was also defined as "on, upon" (LT1:256, MC:216). Prefixed or- is translated "up" in ortil, q.v.