As others have already stated, relax can mean more than one thing; as defined below:
"relax [rɪˈlęks]vb1. to make (muscles, a grip, etc.) less tense or rigid or (of muscles, a grip, etc.) to become looser or less rigid
2. (intr) to take rest or recreation, as from work or effort on Sundays, she just relaxes she relaxes by playing golf
3. to lessen the force of (effort, concentration, etc.) or (of effort) to become diminished
4. to make (rules or discipline) less rigid or strict or (of rules, etc.) to diminish in severity
5. (intr) (of a person) to become less formal; unbend"
In aiki arts, normally the focus is on definition 1 above - however, many confuse the objective with the other definitions.
Personally, I use the term 'un-tensed connected extension' to describe what I mean for relaxing muscle tension without collapsing into a noodling type of movement.