1932, up front "in the front," from up + front (n.). Meaning "honest, open" is from 1970; that of "paid in advance" is from 1967.
he was upfront about his intentions
update
updraft
upend
*uper
upfield
upfront
upgather
upgrade
upheaval
upheld
uphill
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}