These are the fifth and sixth postponements of the 2020-21 season to date.
Neither Boston nor Washington would have had the minimum eight players required for their respective games due to COVID-19 testing and contact tracing.
The Celtics and Magic are also scheduled to play Friday. The status of that game isn't immediately clear, ESPN's Adrian Wojnarowski reports.
This is the Celtics' third postponement in a row. The team did not play its scheduled contest Sunday against the Miami Heat and was not slated to play Tuesday against the Chicago Bulls.