Which seven letter English word is said to contain thousands of letters in this playful riddle?

Introduction / Context:
This riddle is a neat example of wordplay where the same word letters is used with two different meanings. The puzzle says that there is a seven letter word that contains thousands of letters. It appears contradictory at first, because a seven letter word obviously has only seven alphabetic characters. The trick is to recognise that letters can also mean written messages that are sent in the post. Many verbal reasoning questions use similar jokes to check whether candidates can shift between literal and figurative meanings quickly.

Given Data / Assumptions:
- The answer must be exactly a seven letter English word. - That word is described as containing thousands of letters. - The second use of letters most likely refers to written mail. - The riddle is playful, not a strict mathematical statement.

Concept / Approach:
The key idea is to think about places or containers for written letters. In everyday life, letters are stored and delivered in mailboxes or postboxes. The word mailbox has exactly seven letters and describes a physical box that can hold many individual postal letters. Therefore, in a wordplay sense, the seven letter word mailbox can contain thousands of letters. Once you notice this shift in meaning, the puzzle feels straightforward. This pattern of using two senses of a single word is very common in English puzzles and is important for exam preparation.

Step-by-Step Solution:
1. Confirm that the answer must be a seven letter word. 2. Recognise that letters has two meanings: alphabet symbols and written messages. 3. Think of common nouns that hold or manage written letters, such as mailbox, postbox or letterbox. 4. Count the letters in mailbox and see that it has seven characters. 5. Conclude that mailbox is a seven letter word that can physically contain thousands of postal letters.

Verification / Alternative check:
To verify, spell mailbox: M A I L B O X. There are seven alphabetic characters. Then imagine a large community mailbox in an apartment building. Over time, it may receive hundreds or thousands of mailed letters. The statement that this seven letter word contains thousands of letters is then clearly true in the sense of the riddle. Other options like library, notebook, envelope and dictionary may involve words or pages, but letter is not their main defining feature in the same clean way.

Why Other Options Are Wrong:
Library has seven letters but contains books, not items specifically called letters. Notebook stores pages and notes. An envelope holds letters, but the word envelope has eight letters, not seven, so it fails the first requirement. Dictionary is longer than seven letters and is about words and meanings. Mailbox alone satisfies both conditions: seven characters in its spelling and the ability to contain thousands of postal letters, making it the best fitting answer.

Common Pitfalls:
Some students rush and choose envelope because they associate it strongly with letters, but they forget to count the number of alphabet characters in the word. Others overcomplicate the puzzle and think about electronic mail or folders in computers, which is not necessary. It is often safest in such riddles to check simple conditions like letter count before jumping to a conclusion. Careful counting and awareness of multiple meanings of everyday words give a strong advantage in language based reasoning tasks.

Final Answer:
The seven letter word that can contain thousands of written letters is mailbox.