Spindly means long, thin and looking too weak. Spindly legs, a spindly plant, spindly branches.
The word contains a judgement — spindly says the thinness is a fault, where slender says it is fine. A spindly seedling has usually been grown in too little light and stretched towards it. It comes from spindle, the thin rod used in spinning.
1adjectivespindlyLong, thin and looking too weak.
“The newborn foal stood up on its long, spindly legs.”
spindly is a quality of shape.
From spindle + -y.
Etymology from Wiktionary, CC BY-SA