General use as a modifier, with the sense ‘consisting of or extending over seven days’.

Each week; per week; weekly.

Every week; in every seven-day period; spec. once a week.

Once a week; weekly. (humorous or affected.)

(a) Occurring every three weeks, or lasting for three weeks. (b) Usually, occurring, appearing, or operating three times every week. Originally U.S.

that lasts for a week.