headache

noun

head·​ache ˈhed-ˌāk 

1

: pain in the head

2

: a vexatious or baffling situation or problem

… meetings had become a giant headache.

—Franklin Foer

headachy adjective

or less commonly headachey

ˈhed-ˌā-kē 

Synonyms of headache

• job
• killer
• burden
• effort

Examples of headache in a Sentence

I'm starting to get a headache.

The symptoms include fever and headache.

The city's biggest headache is traffic.

Managing your finances can be a real headache.

Recent Examples on the Web

Her symptoms included headache, hallucinations, vomiting, and a high fever, all symptoms of a rapidly expanding pituitary tumor, per the authors. — ArsTechnica, 2 Nov. 2026

Roughly 86% of the intervention group reported mild to moderate side effects, primarily during the early weeks, including headaches, fatigue, dizziness and constipation, though researchers noted that no severe medical complications occurred. — Khloe Quill, FOXNews.com, 2 Nov. 2026

Common side effects with lenacapavir include injection site reactions, headache and nausea. — ABC News, 2 Nov. 2026

Other important symptoms of a stroke are a severe headache, confusion and numbness on one side of the body. — Diane Webber, NPR, 1 Nov. 2026

Word History

First Known Use

before the 12th century, in the meaning defined at sense 1

Phrases Containing headache

• cluster headache
• ice-cream headache
• pre-headache
• sick headache
• splitting headache
• tension headache

Rhymes for headache

• awake
• backache
• beefsteak
• betake
• cheesecake
• cupcake
• daybreak
• earthquake
• forsake
• gouache
• handshake
• heartache

Video

An Abbreviated History of American English Spelling

TRANSCRIPT

Welcome to Ask the Editor, I'm Peter Sokolowski, Editor at Large at Merriam-Webster.
 
Many people over the years have tried to simplify English spelling. Benjamin Franklin even worked out an entire new phonetic system and George Bernard Shaw funded research into creating a whole new alphabet. But probably the only successful spelling reformer in the history of the English language was Noah Webster, who made the changes that we recognize today as American-English spelling.
 
Webster was a patriot through and through and he passionately believed that the new nation should have its own language. He said that a national language is a national tie and since America was made up of people from different cultures and classes, it was important to establish that language right away as being distinct from that of the British colonizers.
 
Webster's first book wasn't a dictionary, but a spelling book. It was a kind of textbook with exercises and readings called the Blue Back Speller and was used for generations to teach reading and writing. A few years later, he published an essay advocating a radical simplification of English spelling.
 
For example, he wanted to spell ache, as in headache, A-K-E, soup with a double o, and to drop the silent E at the end of words like determine.
 
He would have changed tongue to T-U-N-G, and women to W-I-M-M-E-N.
 
Those these changes might have been phonetically logical, most of them were just too radical.
 
However, some of his recommendations caught on.He dropped the U in words like color, humor, and honor, and changed the S to Z in words like civilization and the R-E to E-R in words like center and theater.
 
Webster believed that the moment right after the Revolution was the time for a declaration of cultural independence and his spelling book and dictionaries marked the beginning of the true recognition of American English.
 
Watch for more segments of Ask the Editor here at merriam-webster.com.

Kids Definition

headache

noun

head·​ache ˈhed-ˌāk 

1

: pain in the head

2

: an annoying or baffling situation or problem

headachy

-ˌā-kē 

adjective

Medical Definition

headache

noun

head·​ache ˈhed-ˌāk 

: pain in the head

called also cephalalgia

headachy

-ˌā-kē 

adjective