For me all the verbs bellow mean the same thing. My dictionaries, confirm this fact. But I guess something is wrong with this belief of mine and their usages are different. I would be thankful if you could explain me how the following verbs semantically differ from one another?

1) To understand something

2) To find something out

3) To discover something

4) To realize something

5) To perceive something

P.S. I guess giving some specific examples with different senses in which only one or all the possible choices from among my suggested verbs can be used, would be very effective for me to discover the exact usage of each verb.

  • There are many, many contexts where any one of these verbs could be replaced by a different one with no difference in meaning whatsoever. But there are also contexts where you can't do this, because each verb will have specific usages that aren't shared by any/all of the others. Thus, "If the taxman investigates, you will be found out" (your guilt will become known, not the fact of your existence). Or "Martin Luther King did not live to see his dream realised" (turned into a reality). Nov 30, 2014 at 13:32

2 Answers 2


Assuming you have only a tiny piece of paper and want to jot down the gist of the most common uses (each has alternate meanings and many times they can be used interchangeably, either because the speaker is speaking loosely, or figuratively):

1) To understand something : to comprehend it

Do you understand how RNA transcription works?

2) To find something out : to learn about something by asking deliberately

I'll find out when the shop opens tomorrow morning by phoning the proprietor.

b) or accidentally e.g. by overhearing it being spoken about, etc

I found out that Mary and John are going to have a baby. She was trying on maternity clothes in the department store.

3) To discover something : to learn something through experimentation

Vaccines are discovered by scientists.

4) To realize something : to suddenly understand or recall something

I just realized that we cannot go to the beach next Saturday; that's the day of John's wedding.

I just realized that Superman is actually Clark Kent. (or that Clark Kent is actually Superman).

5) To perceive something : to sense something; to "see" it figuratively

I perceived that something was amiss with their relationship. John seemed on edge and Mary was distant.


Broadly, and leaving aside uses where these verbs have unrelated meanings:

  1. Understand and perceive are stative verbs: they designate a state rather than an event. States are durative—they continue over time—but they are atelic—they do not have an end or goal. States are not dynamic: no energy or effort is required to maintain a state.

    Understand usually implies a state of knowledge: you know how something works or how to do something or the meaning of what somebody has said, and so forth. Perceive usually implies a state of awareness: the thing you perceive is present to your consciousness, while what you know may lie in the background. To perceive something does not necessarily imply that you understand it.

    I perceive that you are puzzled, but I do not understand why you are puzzled.

  2. Find out and discover are eventive verbs: they designate events and imply a change of state from ignorance to knowledge. They are, specifically, achievement verbs: they are telic, having an end or goal (the state of knowledge), but they are ordinarily nondurativefind out and discover designate the timeless moment in which you pass from ignorance to knowledge.

    Both find out and discover may be used in a non-dynamic sense, of something which 'happens' to the subject, but only find out may be used dynamically, to designate the result of the subject's efforts. And both may be used with facts or events as their object, but only discover may be used with physical substances or objects.

    I have just {found out/discovered} that today is her birthday. BUT
    I will {find out/discover} when her birthday is. AND
    Columbus {found out/discovered} America.

  3. The primary sense of realize is eventive; in this sense it is used non-dynamically, like discover, but only with facts and events, like find out.

    I just realized that today is your birthday. BUT NOT Columbus ∗discovered America.

    But unlike discover and find out, realize may also be used as a stative, equivalent to know or understand:

    I realize that you are angry.

These are the ‘core’ aspectual uses of these verbs; but in particular contexts they may be recategorized. For instance, we do not ordinarily use the progressive construction with stative verbs, because the progressive construction confers durativity and they are already durative:

I understand algebra, not I am understanding algebra.

But these statives may be used in the progressive when the state they designate is felt to be ‘gradable’, divided into degrees of knowledge or awareness:

I am perceiving more and more what a nice fellow Kevin is. = My awareness of Kevin’s niceness is increasing.

Similarly, the achievement verbs may be cast in the progressive with the implication that the the action is repeated. This recategorizes them as activity verbs, which are atelic (because the action can be repeated indefinitely) and durative (because the repetition takes place over time):

I am {discovering/finding out} more and more about algebra every day. = Every day I discover something new about algebra.

And when the stative verbs are used in the past form, which treats them as perfective, completed wholes, they are sometimes recategorized as telic nondurative achievements (see below), signifying the passage from ignorance to knowledge. This is particularly the case if a nondurative adverb is employed.

I suddenly understood (= realized) that today was her birthday.

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