Copying from multiple sources
The author hides plagiarism by copying from multiple sources, modifying the sentences to make them come together while conserving most of the original terminology. For example, if the student modifies this sentence from the first passage - "Einstein said that time is relative to the entities experiencing it. One man's second can be another woman's forty years." And then he/she modifies this sentence from the second passage "A clock traveling at the speed of light is slower when compared to a stationary observer than a clock at rest would." And combines them in his paper, then it would be "Copying from multiple sources."