Meditation
"Meditation" is an umbrella term referring to three Sanskrit words
Dharana (dhaa-ruh-nuh)
Actions that we take. Focusing/technique. A verb - something you can do like a specific meditation method.
Dhyana (dh-yaan-nuh)
A state of mind you may enter into. Typically peaceful. You do Dharana to prepare for Dhyana, like getting ready for sleep but you can't "do" sleep, it just happens. The "no mind" state. Where medical benefits start to be measurable.
Samadhi (suh-mah-dhi)
A temporary state of enlightenment. Like REM sleep in the Dhyana sleep metaphor. Where personality change can be measurable.