1. 无重量的;轻的
Something that is weightless weighs nothing or seems to weigh nothing.

2. 失重的
A person or object is weightless when they are in space and the earth's gravity does not affect them, so that they float around.

1. having little or no weight or apparent gravitational pull
light

e.g. floating freely in a weightless condition
a baby bat...fluffy and weightless as a moth
jackets made of a weightless polyester fabric