A big part of learning English is learning new English vocabulary. Most teachers can tell you that it’s very common for students to study all kinds of new vocabulary words and their definitions. They can pass a multiple choice test or match the words to their definitions in an exercise, but when students try to use these words in sentences, their sentences are confusing or incorrect. That's because a word is more than just its definition, more than just denotation.
There are three very important aspects of a new word that you should be sure to learn: denotation, connotation, and collocation.
The denotation of a word is its actual meaning, the definition that you will find in the dictionary. Most students know that this is a very important part of learning new vocabulary, but it is not the only thing you need to know.
Connotation is a little more difficult. Connotation is a suggestive meaning, the emotions and feelings that a word is connected with. A word can have positive or negative connotations. For example, the words skinny and slender have the same denotation, but skinny generally has a negative connotation (it sounds like too thin), while slender sounds positive and attractive. Another example: the words woman and lady are synonyms, but lady has connotations of elegance and grace, while woman is more neutral. Female is another synonym, but it connotes biology or science. Your mother is a female, but it would be unusual to use that word to describe her.
Collocation is another important aspect of words in a language. Some words usually happen with other words. This is collocation. Many students will learn the word party, which is an easy word to understand. But when they make a sentence, they will say make a party or do a party, translating from their own language. In English, though, party collocates with have. In English we have a party. So just learning what the word party means is not enough. We also need to learn the word's collocates.