crux — The crux of a problem or argument is the most important or difficult part of it which affects everything else.
ducks — any of numerous wild or domesticated web-footed swimming birds of the family Anatidae, especially of the genus Anas and allied genera, characterized by abroad, flat bill, short legs, and depressed body.
dux — British. the pupil who is academically first in a class or school.
lox — a clear, pale blue liquid obtained by compressing oxygen and then cooling it below its boiling point: used chiefly as an oxidizer in liquid rocket propellants.
lux — a unit of illumination, equivalent to 0.0929 foot-candle and equal to the illumination produced by luminous flux of one lumen falling perpendicularly on a surface one meter square. Symbol: lx.
shucks — a husk or pod, as the outer covering of corn, hickory nuts, chestnuts, etc.
sucks — to draw into the mouth by producing a partial vacuum by action of the lips and tongue: to suck lemonade through a straw.
deluxe — Deluxe goods or services are better in quality and more expensive than ordinary ones.
Three-syllable rhymes
radiant flux — the time rate of flow of radiant energy.
Four-or-more syllable rhymes
luminous flux — the rate of transmission of luminous energy: expressed in lumens.
magnetic flux — the total magnetic induction crossing a surface, equal to the integral of the component of magnetic induction perpendicular to the surface over the surface: usually measured in webers or maxwells.
