A Muse on Teaching/Learning vocabulary: note how much easier it is to define words in context, for example as pairs of words, than as singles. As an example think of a quick definition for "primary". Not so hard, it takes a few words, and requires a little bit of thinking to cover the possibilities because sometimes it refers to "first" other times it is better described as "basic". It takes a bit of maneuvering to cover all the bases.
Now let's define another word, "motivation". How would you define that? Takes a bit of thinking. Not terribly hard but a little more difficult than "primary" I'd say.
Now combine the words and try the phrase "primary motivation".
Because each word constrains the meaning of the other word it is much easier to define the phrase than to define each word separately.
Therefore, it might be much more useful and and learner friendly to define a word in context rather than as a loner. Let's call this the "word buddies" understanding of vocabulary.
Excellent summary of how to do extensive reading