This root comes from the Latin word "sidere," which means "to sit." It's often found in words related to:
* Observation: Like "consider", which means "to think about something carefully," as if sitting and reflecting on it.
* Position: Like "insider" (someone who has access to confidential information) and "outsider" (someone who does not).
* Stars: Like "constellation", referring to a group of stars that appear close together in the sky.
The "-sider" ending often implies a sense of being placed, positioned, or observing from a particular point of view.