Word of the Week: weir (ˈwer, ˈwir) Definition (noun) 1. a fence or enclosure set in a waterway for taking fish 2. a dam in a stream or river to raise the water level or divert its flow In Context "Without the weir, the ocean tides could flow in and out, creating a predominantly saltwater system." Phil Diehl, sandiegouniontribune.com, "Decision on Buena Vista Lagoon project likely delayed until summer," 22 Apr. 2018