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 (verb), retroacts; retroacted; retroacting
To do something in return or to act in opposition: When Mr. Timmons was voted into office, he retroacted some of the decisions that were made previously by the former chairman.
retroaction (s) (noun), retroactions (pl)
1. A reaction or a counter action: When Grace suffered from being overweight, she decided on retroaction, or a response to this problem by going on a strict diet.
2. An act that is influenced by a past circumstance: Retroaction was needed when planning the rebuilding of the town after the terrible flooding that destroyed so many buildings and land.
retroactive (adjective) (not comparable)
Regarding something that has an effect on a circumstance in the past: At work it was decided that the wages for the colleagues would be retroactive and the fellow workers were so happy to receive the extra pay for the job they did in the past!
retroactively (adverb) (not comparable)
Concerning how an event takes effect beginning on a date in the past: Mr. Smith was paid retroactively for his good work in the office going back to the beginning of the year,
retroactivity (s) (noun), retroactivities (pl)
The condition of affecting things or occurrences of the past; retroactiveness: The members of the meeting were opposed to the rule of retroactivity in situations when there had been a unanimous vote to settle the past issues.
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.
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.
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.