Abarim Publications' online Biblical Greek Dictionary
The verb πλεθω (pletho) means to fill or be full. For obvious reasons, this verb is often associated with water (and thus vessels and rivers), and since the ancients understood the similarity between water and light (see our article on the Hebrew verb נהר, nahar, which means both to flow and to shine), our verb πλεθω (pletho) may also be used to describe a filling with knowledge or emotion (Luke 4:28, Acts 3:10) and of course the Holy Spirit (Luke 1:15, Acts 2:4). Our verb may be used to describe an event "filled" with people (Matthew 22:10), a ship with fish (Luke 5:7), or a sponge with vinegar (Matthew 27:48). A period in time may be fulfilled: as stint in office (Luke 1:23), or a pregnancy (Luke 1:57).
Altogether our verb is used 24 times in the New Testament, see full concordance. Note that 8 of these occur in the first two chapters of Luke, detailing the birth of Jesus Christ, and 9 in the Book of Acts. Both these books were written by Luke, whose name means Light. Later Jesus would explain that he was the well of Living Water (John 4:14).
From our verb πλεθω (pletho) or its alternate form πιμπλημι (pimplemi), both meaning to fill or be full, come the following derivations:
- Together with the preposition εν (en), in, on, at, by: the verb εμπιπλαω (empiplao), meaning to fill in or satiate. This verb describes the same process as the parent verb, namely to make full, but places an emphasis on the vessel that's being filled: the hungry (Luke 1:15), baskets (John 6:12), hearts (Acts 14:17). This verb is used 5 times; see full concordance.
- The noun πληθος (plethos), meaning literally a fullness (hence our English word "plethora"), but both in the Greek classics and the New Testament only used to describe a very large amount: a crowded mass of angels (Luke 2:13), fish (Luke 5:6, John 21:6), stars (Hebrews 11:12), sins (James 5:20, 1 Peter 4:8) and even fire wood (Acts 28:3), but mostly of people. Our noun usually describes a bulging grid-locked throng, but it may also describe a relatively small group of bodies (Luke 19:37, Acts 6:2); the crucial nuance of our noun is that however many there are, they fill the entire available space. It's used 32 times, see full concordance, and from it in turn come:
- The noun πλησμονη (plesmone), meaning a filling, a satisfying to capacity (Colossians 2:23 only).