πλόος, πλούς genitive, -όου, -oῦ (and in late writers also πλοός, like νοός from νοῦς), ὁ (< πλέω), [in LXX: Wis.14:1 * ;] a voyage: Refs Act.21:7 27:9-10.† (AS)
Thayer:
1) a voyage
πλόος
ploos
plo'-os
From G4126; a sail, that is, navigation
πλέω, πλεύω
pleō pleuō
pleh'-o,plyoo'-o
The first is another form for the second which is used as an alternate in certain tenses; probably a form of G4150 (through the idea of plunging through the water); to pass in a vessel