Many words in English have one side that is commonly used, while their pairs are often ignored. For example, you might be 'disgruntled' but have never been 'gruntled.'
Language evolves and new words are created when two concepts come together. Words like 'email' started as 'electronic mail' and have changed over time.
As words change, their pronunciation also shifts. For instance, 'bookshop' is pronounced differently than 'book shop,' showing how language and speech develop over time.