retro-, retr-

(Latin: back, backward, backwards; behind)

arrear (s), arrears (pl)s; arrearage (s), arrearages (pl)
1. An unpaid or an overdue debt or an unfulfilled obligation; usually used in the plural form.
2. A situation when someone is behind in fulfilling obligations: "His car payments are in arrears; and as a result, his car may be repossessed."
3. Money that is not paid when due usually, the sum of a series of unpaid amounts; such as, rent, installments on an account, a promissory note, or monthly child support.

Sometimes these are called "arrearages" or the state or condition of being in arrears.

4. Arrearages are overdue alimony or child support payments.

Child support arrearages can't be discharged in bankruptcy, and courts usually will not retroactively cancel them; so, a spouse or parent who falls on tough times and is unable to make payments should request a temporary modification of the payments before the arrearages build up.

5. Etymology: from Old French ariere, "behind, backward"; from Common (Vulgar) Latin ad retro, from Latin ad, "to" + retro, "behind".
retroact
retroaction
retroactive
retroactively
retroactivity
retroauricular
retrocede (ret" roh SEED) (s) (noun), retrocedes (pl)
1. An action that involves giving something back to a person; such as, land or a territory: The local tribal groups petitioned the government for an act of retrocede, to return their traditional property to the governance of the Native councils.
2. A move back or away from a limit, a point, or a mark: The community was hoping that there would be a retrocede of the floodwaters that have caused so much damage.
3. Etymology: from Latin retrocedere, "to go back" from retro-, "back" + cedere, "to go".
retrocession (ret" roh SESH uhn) (s) (noun), retrocessions (pl)
1: A reversal or return to a previous condition: After a period of  barking, Pretty Boy, Nicole's favorite spaniel, demonstrated a retrocession and stopped making the loud noise and curled up to go back to sleep.
2. A medical condition that reveals the signs of an illness, previously noted on the outside of a patient, that begin to appear internally: The large cancerous sore on Monica's forearm seemed to be getting smaller; however, the oncologist informed her that there appeared to be evidence that a  retrocession of the disease was developing on some of her other body parts.
retrocolic
retrocursive (adjective), more retrocursive, most retrocursive
Characterized by running, or stepping, backward: Bryan's cousin had a strange mental condition in that he was always making more retrocursive movements than the normal forward walking or running actions.
retroflection, retroflexion
1. The act of bending backward.
2. An articulatory gesture made by turning the tip of the tongue back against the roof of the mouth.
3. A turning or tilting backward of an organ or body part.
4. A bending backward of the body of the uterus upon the cervix.
5. The acoustic quality resulting from retroflex articulation.
retroflex
1. Bent, curved, or turned backward.
2. Pronouncing certain words and/or letters with the tip of the tongue turned back against the roof of the mouth.
3. A sound pronounced with the tongue in retroflex position, as the sound "r" in some varieties of English.
retrogradation
retrograde