1
on Friday
表示具体某一天时，用介词on。
The meeting is on Friday.
会议在星期五举行。
星期五；周五
先理解核心含义，再看它在真实句子里的用法。
星期五；周五
Friday
The meeting is on Friday.
会议在星期五举行。
在许多宗教传统中为一周的第六天,在采用 ISO 8601 标准的系统中为一周的第五天；即穆斯林安息日；介于星期四与星期六之间。
The sixth day of the week in many religious traditions, and the fifth day of the week in systems using the ISO 8601 norm; the Muslim Sabbath; it follows Thursday and precedes Saturday.
一周的第六天；第五个工作日
the sixth day of the week; the fifth working day
We have an important meeting scheduled for Friday morning.
我们安排了一个重要的会议在星期五早上举行。
My sister usually visits us on Friday evenings after work.
我姐姐通常在星期五下班后的晚上来看我们。
Are you free this Friday to join us for dinner?
你这个星期五有空和我们一起吃晚饭吗？
表示具体某一天时，用介词on。
The meeting is on Friday.
会议在星期五举行。
表示每周重复。
We have a team meeting every Friday.
我们每周五都有团队会议。
Friday morning/afternoon/evening/night 表示一天中的具体时段。
They often go out on Friday night.
他们经常在周五晚上出去。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
在星期五
The meeting is on Friday.
会议在星期五。
星期五晚上
We go out every Friday night.
我们每个星期五晚上都出去。
耶稣受难日
Good Friday is a public holiday in many countries.
耶稣受难日在许多国家是公共假日。
下星期五
I have an appointment next Friday.
我下星期五有个预约。
星期五下午
The office closes early on Friday afternoon.
办公室星期五下午提前关门。
便装星期五
We can wear jeans on casual Friday.
在便装星期五我们可以穿牛仔裤。
忠实的男助手；得力干将
He's been my man Friday for over ten years.
他做我的得力助手已经十多年了。
女助手；女秘书
She works as the boss's girl Friday.
她是老板的女秘书。
周五的轻松心情（期待周末）
I've got that Friday feeling and can't concentrate on work.
我有那种周五的轻松心情，无法集中精力工作。
星期五我恋爱了
The song 'Friday I'm in Love' is often played on Fridays.
歌曲《星期五我恋爱了》常在星期五播放。
是星期五，星期五，必须在星期五尽情狂欢
Rebecca Black's 'Friday' became a viral hit about the day.
丽贝卡·布莱克的《星期五》成为了关于这一天的一首病毒式热门歌曲。
Use Friday naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想“福来day”，星期五下班后幸福就要来了。
neutral; used in everyday conversation, scheduling, and calendar contexts
All of these words share the '-day' spelling with Friday. However, note that in standard pronunciation, Friday ends with /di/ (like in 'beady'), while the other weekdays typically end with /deɪ/ (like 'day' /deɪ/). In rapid speech, some speakers may reduce the final syllable to /di/ for all, but the careful pronunciation differs. The part 'day' is a transparent spelling chunk common to all days of the week.
Dictionary facts from ECDICT, WIKTIONARY.