[Meaning ones who/which are] hastening backwards.1
"[Will you] not [get] out? [Will you] not set your foot going backwards?" Ajax says [this] to Tecmessa, his spear-won bride.2
[1] Likewise or similarly in other lexica. The headword, nominative plural of this adjective, is not extracted from the quotation given (which has the accusative singular) but from Homer, Iliad 21.456 (web address 1); see the scholia there.
2Sophocles, Ajax 368 (web address 2), with scholion.