Learn English – Talking about skills level, which adjective fits better: “intermediate” or “medium”

Different dictionaries order their definitions in different ways. Some are diachronic, some order by senses, some by frequency of use - as with the Collins Cobuild.

The larger issue is that some words are used in specific situations, usual in certain contexts, which is more important than the order of their meanings as given in dictionaries.

For example: You can use the term "read" to mean "understand," as in, "I read you." This might be uncommon usage in an operating theater, but preferred in aeronautic communications.

Also: Word choice is often strongly influenced by surrounding words. More could be said on this subject if you provide the words and context in question.

"Redundant" involves repetition. In the following example, there are two examples of redundancy: "This blue, azure shirt is torn and ripped." Blue and azure are redundant, and torn and ripped are redundant. Note that these redundancy pairs do not include words that are exactly synonymous, but which are close enough in meaning that one would usually consider them redundant. Two points here: 1. Neither word in such a pair is necessarily the redundant one; either one can be considered redundant, depending on which one you consider to be the more important, useful, or accurate one in the given context. Commonly, the second word is considered the redundant one, but that is merely because the first word got a chance to establish itself before the second one came along; if you were revising the text, you might choose to keep the second, not the first. 2. The same word repeated ("this blue blue shirt") is an example of redundancy, but this is usually done for emphasis, or for poetic effect, and so is seldom saddled with the accusation of redundancy. Thus, "redundant" does tend to carry the implication of an unnecessary repetition.

A tip: To help you remember this, note that "redundant" begins with "re," as in "repetition." That piece of these words means "again."

"Superfluous," on the other hand, refers to something that is more than what is necessary. Think of water running over the rim of a glass when you continue to pour water into it beyond its capacity. The water over- (super) flows (fluous). Often something superfluous is so because it is needlessly repetitive, and this confuses the picture a bit. But in my opinion, "superfluous" is better used when the element is not repetitive, but is genuinely not needed, as in this example: "After George embedded the fence post in thirty pounds of concrete buried underground, the brick he balanced atop the post to hold it down was superfluous."