Luke 20:43 Till I make thine enemies thy footstool.
In order that I might place those hated of yours a footstool of those feet of yours.
This verse uses the actual Greek word for footstool. The version in Matthew 22:44 doesn't use the same word, but a more general one. The last part of this verse in Greek is missing in the KJV both here and in Matthew.
The word translated as "till" means "until" but it also means "in order that."
An untranslated word appears here indicating the following is possible but not certain.
The Greek word translated as "I make" is translated from a Greek word that means primarily "to put," and "to place," but which has many related meanings as well. This verb is in a form that indicates it is possible but not certain.
The word translated as "enemies" is an adjective meaning "hated" and "hating." It is used as a noun, being introduced by an article, so "the hated" or "the hating."
The Greek word translated as "footstool" means "footstool" and "to reduce under one''s feet." It was the practice of conquerors to place their feet on their conquered enemies' necks.
The Greek word for "feet" appears here, but it untranslated in the KJV. The same word also means "trampling" and "treading upon."
ἕως ἂν θῶ τοὺς ἐχθρούς σου ὑποπόδιον τῶν ποδῶν σου:
ἕως "Till" is from heos which means "until", "till," and "in order that" and "up to the point that."
ἂν Untranslated is the Greek word, an, which is a particle used with verbs to indicate that the action is limited by circumstances or defined by conditions. There is no exact equivalent in English, but it is translated as "possibly," "would have", "might", "should," and "could."
θῶ (verb 1st sg aor subj act) "I make" is from tithemi which means "to put", "to place", "to propose", "to suggest", "to deposit", "to set up", "to dedicate", "to assign", "to award", "to agree upon", "to institute", "to establish", "to make", "to work", "to prepare oneself," "to bear arms [military]," "to lay down and surrender [military]," "to lay in the grave", "to bury," and "to put words on paper [writing]," and a metaphor for "to put in one's mind."
τοὺς ἐχθρούς (adj pl masc acc) "Enemuies" is from echthros, which means "the hated", "the hateful", "the hostile", "the enemy", "the alienated," and "the hating."
σου (pron 2nd sg gen) "Thy" is from sou which means "you" and "your." -- The word translated as "thy" is the possessive form of the second person pronoun.
ὑποπόδιον [uncommon]( noun sg neut acc) "Footstool" is from hypopodion, which means "footstool" and "to reduce under one''s feet."
τῶν ποδῶν (noun pl masc gen) Untranslated is pous, which means a "foot", "a talon [of a bird]," and the concept of "to trample" or "to tred upon."
σου; (pron 2nd sg gen) "Thy" is from sou which means "you" and "your." -- The word translated as "thy" is the possessive form of the second person pronoun.