Antique has a synonym of obsolete. Obsolete has a synonym of outmoded. Since outmode is a transient verb it is always conjugated. But outmode is a word, it is 7 letters and it is a synonym for antique.
A seven letter word that starts with D and ends with T: decrypt
abreastabstainabridgeacclaimacrobataddressadmiredadornedadoringaerobicafflictalignedallowedamassedamendedamateurangelicanswersappealsappliedapprisearguingarousedarrangeartworkashtrayassumedattractaverageaviatoravoiding
Duchess is a seven letter word.
augment
insurer
Include
AttendsAmendedAmountsallowed
attired
A seven (7) letter word that starts with M and ends with O: memento
housing
mobstermockingmodeledmoistenmongrelmonstermorselsmortalsmothersmotoredmournedmounted
laconic