What is the term for a pipe whose thread at both ends leaves a small amount of space?

The term for a pipe whose thread at both ends leaves a small amount of space is referred to as a "short pipe." In this context, a short pipe is typically designed with threads that do not extend all the way to the ends, allowing for a small gap. This design can facilitate easier assembly and connection with other piping components while accommodating expansion and contraction due to temperature changes.

The other options do not accurately capture this specific design characteristic. A long pipe generally has more length but does not imply anything about the threading or the presence of space at the ends. A connector pipe usually refers to a pipe specifically designed to connect two other pipes; it may not have the same threading characteristics. A standard pipe could imply a pipe of regular dimension or specification but does not signify the threading design or space at the ends. Therefore, "short pipe" is the most appropriate and descriptive term for this particular scenario.