When writing a question, above all, it should be your own question, and when writing an answer, it should be your own expert answer. Do not post questions or answers from elsewhere on the Internet.
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A post that contains no original work at all (a paste-only post) is often a sign of a non-expert answer, and may have no value, but this is not always true. Examples of quote-only posts that nevertheless have value might include a quotation that required in-depth research to locate, or that was laboriously reproduced from a print-only source. […] @MetaEd Oct 25, 2016
There has long been a series of objections to answers consisting only of copied dictionary definitions or texts, even instances when they have been correctly formatted and attributed, from outside sources. It is an age-old argument across the Stack Exchange network. The main crux being that these answers are unoriginal and lack the answerer's personal interpretation and insight. That is a fair criticism, but on EL&U we have many users whose first or second language is not English. Their understanding of the finer points in grammar may exceed that of an ordinary native speaker but the confidence to expose their written efforts for inspection can be intimidating. Sometimes the resulting typos and minor errors can be ridiculed in public. We have evidence of this behaviour (Your capitalisation is rather eccentric and You pored over it? Or are you a dog?) beneath the OP's post even though the OP is an American English speaker with ten years of teaching English as a foreign language under their belt.
In single-word requests, sometimes a single word is the answer, the fact that a non-native speaker may get there first and add a dictionary definition, as long as it is properly attributed, should not be discouraged. Ever. If someone disapproves of the effort they can either ignore or downvote the answer.
The OP appears to label posts that contain copied definitions or extracts as examples of plagiarism, but if the sources are clearly attributed and a link is provided, it is not. The OP has confused unoriginality with theft.
Original Answer
Plagiarize verb
transitive verb
: to steal and pass off (the ideas or words of another) as one's own : use (another's production) without crediting the source
intransitive verb
: to commit literary theft : present as new and original an idea or
product derived from an existing source.
Merriam-Webster
The above looks like it is copied from a dictionary and despite the definition being extremely succinct, one would be hard pressed to find a discordant voice. Plagiarism, in my view, is the act of kidnapping a unique string of words created by someone else but passing them off as one's own.
Would my explanation be preferable? Unlike Merriam-Webster, I am not an authority and I do not have 191 years of standing. Some people prefer to cite a dictionary entry to support their answer, and there is nothing wrong with that. On the contrary, it is commendable because a dictionary has authority and we generally trust its impartiality. Quoting a dictionary in an answer shows that the author has at least made a sincere genuine effort.
To be clear, if a user on EL&U properly formats a quotation and attributes the source–as we have done in our posts–it is never plagiarism.
