par·al·lax (par' uh laks) n. An apparent change in the shape of an object, caused by a change in observational position that provides a new line of sight. [French parallaxe, from Greek parallaxis, from parallassein, to change : para-, among; see PARA-1 + allassein, to exchange (from allos, other; see al-1 below).]
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al-1. Important derivatives are: alarm, alert, ultimate, ultra- , alternate, adulterate, other, else, alien, alibi, parallel.
al-1. Beyond. 1. Variant *ol-, “beyond.” a. Suffixed forms *ol-se-, *ol-so-. ALARM, ALERT, ALLIGATOR, EL NIñO, VOILà, from Latin ille (feminine illa, neuter illud), “yonder,” that, from Old Latin ollus; b. suffixed forms *ol-s, *ol-tero-. OUTRé, ULTERIOR, ULTIMATE, ULTRA-, from Latin uls, *ulter, ultr³, beyond. 2. Suffixed form *al-tero-, “other of two.” a. ALTER, ALTERCATE, ALTERNATE, ALTRUISM; SUBALTERN, from Latin alter, other, other of two 3. Extended form *alyo-, “other of more than two.” a. ELSE, from Old English el-, elles, else, otherwise, from Germanic *aljaz (with adverbial suffix); b. ALIAS, ALIEN; ALIBI, from Latin alius, other of more than two; c. ALLO-; ALLEGORY, ALLELOMORPH, ALLELOPATHY, MORPHALLAXIS, PARALLAX, PARALLEL, TROPHALLAXIS, from Greek allos, other. [Pokorny 1. al- 24, 2. an- 37.]

par·a·dox (par' uh docks) n. 1. A seemingly contradictory statement that may nonetheless be true: the paradox that standing is more tiring than walking. 2. One exhibiting inexplicable or contradictory aspects: “You have the paradox of a Celt being the smooth Oxonian” (Anthony Burgess). 3. An assertion that is essentially self-contradictory, though based on a valid deduction from acceptable premises. 4. A statement contrary to received opinion. [Latin paradoxum, from Greek paradoxon, from neuter sing. of paradoxos, conflicting with expectation : para-, beyond; see PARA-1 + doxa, opinion (from dokein, to think; see dek- below).]
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dek-. Important derivatives are: decent, doctor, doctrine, document, dogma, paradox, decorate, dainty, dignity, disdain, indignant, disciple, discipline.
dek-. To take, accept. 1. Suffixed (stative) form *dek-. DECENT, from Latin decere, to be fitting (< “to be acceptable”). 2. Suffixed (causative) o-grade form *dok-eye-. a. DOCENT, DOCILE, DOCTOR, DOCTRINE, DOCUMENT, from Latin docere, to teach (< “to cause to accept”); b. DOGMA, (DOGMATIC); DOCETISM, DOXOLOGY, HETERODOX, ORTHODOX, PARADOX, from Greek dokein, to appear, seem, think (< “to cause to accept or be accepted”). 3. Suffixed form *dek-es-. a. (DéCOR), DECORATE, from Latin decus, grace, ornament; b. DECOROUS, from Latin decor, seemliness, elegance, beauty. 4. Suffixed form *dek-no-. DAINTY, DEIGN, DIGNITY, CONDIGN, DIGNIFY, DISDAIN, INDIGN, (INDIGNANT), (INDIGNATION), from Latin dignus, worthy, deserving, fitting. 5. Reduplicated form *di-dk-ske-. DISCIPLE, (DISCIPLINE), from Latin discere, to learn. 6. (DOWEL), PANDECT, SYNECDOCHE, from Greek dekhesthai, to accept. 7. DIPLODOCUS, from Greek dokos, beam, support. [Pokorny 1. deç- 189.]