slacken, relax
弛 centers on losing tension or strictness: slackening, relaxing, or letting something become loose. The idea applies to physical tightness, mental strain, or a situation that eases up.
弛 combines 弓 (bow) with 也, which likely contributes the sound. The idea of a bowstring being loosened or slackened fits the core meaning of relaxing or losing tension.
A bow 弓 beside 也: imagine the bowstring being loosened after use, so the bow relaxes and goes slack.
For チ, picture a bowstring going slack with a soft 'chee' sound as the tension releases: chee -> チ.
relaxation (e.g. of muscles); becoming flaccid
relaxing; remitting; slackening
slack; slackening; sagginess; flabbiness (skin, etc.)
to slacken; to loosen; to relax; to droop (e.g. loose or flabby skin); to sag (ceiling)
tension and relaxation
tirelessly; perseveringly; without letting up
untiring; steady; persistent
steady; sound; trustworthy
unslacking; unceasing
to slacken; to loosen
looseness and tension
relaxation oscillation
atonic hemorrhage; atonic haemorrhage
flaccid paralysis
muscle-relaxant drug
muscle relaxant
muscle relaxant
tired; weary
lack of (slackness in) military discipline; demoralization