(of arguments, reasons, etc.) well based or logical; sound
that can legally be used for a stated period or in certain conditions
legally effective because made or done with the correct formalities
"a valid inference"
"a valid argument"
"a valid contract"
"the license is still valid"
According to law,..many..documents are not legally valid unless they be stamped.
出自： W. S. Jevons
A Eurocheque book...means you can write a cheque valid in any currency in Europe.