ad
ad — noun
1. an informal short form for an advertisement in print, online, or on TV.
an informal short form for an advertisement in print, online, or on TV.
I saw an ad for guitar lessons on the station wall.
ad for + product or service
On the bus, Esme laughed at a strange toothpaste ad.
The company placed a full-page ad in Saturday's newspaper.
After dinner, Dad skipped the ad and changed the channel.
- advertisement
the full and more neutral form
- commercial
usually means an advertisement on TV, radio, or online video
- promo
more informal and often used for short promotional material
文法句型
an ad for something
place/run an ad
see an ad on TV or online
用法筆記
Informal in everyday speech and headlines. In more careful writing, the full word 'advertisement' is often preferred, especially in formal contexts.
常見錯誤
2. the abbreviation AD, used for Alzheimer's disease, an illness that slowly harms
the abbreviation AD, used for Alzheimer's disease, an illness that slowly harms memory and thinking.
At Dad's care meeting, the doctor said AD was causing his memory loss.
medical abbreviation in records
After her diagnosis, Mei read a booklet about AD at home.
At the clinic, the doctor explained how AD affects memory.
Researchers hope new drugs will slow AD in older patients.
- Alzheimer's disease
the full name, used much more often in general speech
- dementia
a broader group of conditions; AD is one type of dementia
文法句型
AD affects memory
diagnose AD
patients with AD
用法筆記
Seen mainly in medical notes, research writing, and support materials. In ordinary conversation, people usually say the full name 'Alzheimer's disease' instead of the abbreviation.
常見錯誤
ad — adverb
1. used before a year number to show that the year is counted after the birth of Je
used before a year number to show that the year is counted after the birth of Jesus Christ in the traditional Western calendar.
The old temple was first rebuilt in AD 612.
in AD + year
Historians date the letter to AD 79, before the eruption.
A stone cross from AD 950 stands outside the village church.
The textbook marks AD 476 as the end of the empire.
- Anno Domini
the full Latin form
- CE
a modern neutral alternative, usually written after the year
- BC
used for years before the traditional birth date of Jesus Christ
文法句型
AD + year
in AD 430
from AD 950
用法筆記
Placed before the year number in traditional English dating. Many modern books instead use 'CE' after the year, especially in academic or interfaith writing.