gleichzeitig
as well
at the same time
coincident
coincidental
concomitan
concomitant
concurrent
concurrently
contemporaneous
contemporaneously
contemporarily
contemporary
coresident
homo-chronous
homochronous
isochronal
isochronous
on the fly
simultaneous
simultaneously
simultanous
synchronal
synchronic
synchronical
synchronistic
synchronous
synchronously
while