Any quick search will reveal some staggering pieces of data for you about words in the English language. The most recent record shows that there are over 170,000 words in the English language. This doesn't include the 50,000 words that are now considered obsolete. The average native English speaking adult knows over 35,000 words. Native English speakers as young as four already know 5,000 of those words, and will learn at least one word a day until they reach middle adulthood! With this many words to learn, it's easy to find long words in English.
Do you want to expand your vocabulary and learn more long words in English? You're in luck! We have compiled 25 of the most challenging words in the English language.

25 Most Challenging Long Words in English
There are many factors to consider when assessing the most challenging words in the English language. First, these words are difficult to spell. Whether it is because of silent letters or letter arrangements, people commonly stumble over the correct arrangement of letters in these words.
Next, they are uncommon, and you are unlikely to hear them in regular conversation. The origins of these words range from Western and Eastern cultures, and some words are very niche.
Finally, these are long words in English, making them more complex than our day-to-day jargon.
Here is our curated list of the 25 most challenging long words in English.
Guayabera
noun, gua·ya·bera
A short-sleeved lightweight shirt traditionally worn untucked. Connected the Puerto Rican and Cuban cultures, these shirts generally feature tropical patterns.
Aniseikonia
noun, an·is·ei·ko·nia
A defect of the eyes, which results in the two eye's prescription differing. This causes the size of an object to differ between eyes, causing the eyes to magnify and shrink simultaneously.
Ginglymus
noun, gin·gly·mus
A joint at a bending point that can only move on a singular plane (like an elbow or knee).
Eleemosynary
adjective, el·ee·mo·sy·nary
relating to, or supporting by a charity.
Hagiographer

noun, ha·gi·og·ra·phy
A biographer who focuses solely on the biographies of saints.
It can also be somebody who idolizes the person they are writing the biography for.
Rajpramukh
noun, raj·pra·mukh
The constitutional head of a state of India formed from several former princely states who is elected by a council of rulers.
Connoisseur
noun, con·nois·seur
An expert on a specific topic. Somebody who knows and appreciates the unique subtleties of something.
Ferruginous
adjective, fer·ru·gi·nous
Something that contains or looks like iron.
Erubescent
adjective, r·u·bes·cent
To turn something the color red (or reddish).
Mignonette

noun, mi·gnon·ette
- an annual garden herb, is known for creating fragrant white flowers.
- A sauce made with vinegar, pepper, and herbs, typically served with oysters.
Obliviscence
noun, ob·li·vis·cence
The act of being forgetful.
Gesellschaft
noun, ge·sell·schaft
Social relations based on impersonal ties as a duty to a society or organization.
Demitasse
noun, demi·tasse
A small cup of black coffee (also what you call the cup the coffee is served in).
Hackamore
noun, hack·a·more
A harness with a loop that can be tightened (or loosened) over the nose. This replaces the bit and provides a slip noose passed over the lower jaw.
Tomography
noun, to·mog·ra·phy
A method of producing a three-dimensional image of the internal structures of a solid object (such as the human body or the earth). This is achieved through observing and recording how different elements pass through the structures.
Sesquipedalian
adjective, ses·qui·pe·da·lian
A word that has many syllables. A long word.
Expugnable
adjective, ex·pug·na·ble
Something likely to be captured.
Embouchure
noun, em·bou·chure
The use of the mouth (teeth, tongue, and lips) to successfully play a woodwind instrument.
Clerihew
noun, cler·i·hew
A light verse quatrain rhyming AABB and usually dealing with a person named in the initial rhyme.
Apoplexy

noun, ap·o·plexy
medical stroke or hemorrhage into vital organs.
A state of intense anger.
Griffonage
noun, grif·fo·nage
Illegible handwriting, usually associated with carelessness.
Calefacient
adjective, cal·e·fa·cient
The process of making something warm.
Rhinorrhagia
noun, rhi·nor·rha·gia
Nosebleed
Plangency
noun, plan·gen·cy
The state of being plain. Hearing a loud and reverberating sound.
Consanguine
adjective, con·san·guine
Being related through blood and/or origin.

Want to Master Complex Words like These?
Learning long words in English can seem like a daunting task, but there are ways to hack defining words on the fly. There are a handful of tricks to use when defining words that you don't know.
First, it is important to learn the affixes in English. Affixes, or prefixes and suffixes, are generalized sets of letters that help readers define the word. For example, the prefix un- means to take away. So when you see the word undo, you can quickly define it as "take away doing."
While the definition might be a little choppy, you get the idea.
If you have a strong command of the affixes, roots, and stems of long words in English, you will be able to have a better chance of defining them without the use of a dictionary.
If you are preparing for an exam with a vocabulary section (like the GRE), it is important to have these skills. Since it's nearly impossible to memorize all 170,000 words in the English language, you will have a better chance at success by learning tricks like this to decode words on the fly.
What is your best tip for defining long words in English? Let us know in the comments below!