Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

[Q]: Sentence1: Arthropods Arthropods have jointed segmented exoskeletons. 
Sentence2: Insects have jointed segmented exoskeletons.
[A]: exoskeletons


[Q]: Sentence1: If there is sun, there is sunlight, there is day. 
Sentence2: Energy enters ecosystems from the sun.
[A]: sun


[Q]: Sentence1: Streams A stream is a sequence of characters. 
Sentence2: a sequence of characters may start with runoff or water seeping out of a spring.
[A]:
characters