bow (arrow)
弩 centers on a large, powerful bow, specifically a crossbow-like weapon that shoots arrows. The meaning is straightforward: a bow for launching arrows.
弩 combines 奴 (phonetic component, possibly suggesting strength or force) with 弓 (bow), indicating a type of bow. The exact historical development is uncertain, but it is a phono-semantic compound.
The top 奴 looks like a person straining, and the bottom 弓 is a bow. Imagine a strong person drawing a massive bow: that's a crossbow.
For ド, picture a bow so powerful it makes a deep 'do' sound when released: do -> ド, the thrum of the bowstring.
crossbow
crossbowman; arbalist
ballista; springald
dreadnought class (of warship)
dreadnought (class of warships)
dreadnought
strong bow; stiff bow
even the strong will grow weak; (even an arrow fired from) a strong bow loses momentum until it cannot even penetrate a piece of thin silk from Lu
superdreadnought (class of warships)
superdreadnought