As Abrams defines it, Zeugma in Greek means “yoking”; in the most common present usage, it is applied to expressions in which a single word stands in the same grammatical relation to two or more other words, but with an obvious shift in its significance. Sometimes the word use is literal in one relation and metaphorical in the other.
That definition may be a little confusing, so basically it is when a single word (usually a verb or adj.) is made to refer to two or more words in a sentence
Example: He arrived in a taxi and a hurry.
- Arrived is used to describe his arrival in a taxi, and that his arrival was in a hurry.
Example: He opened the door and her heart.
- Open is describing the physical action of opening a door while metaphorically describing the opening of ones heart.
[Kyle Litfin. Section 1G]