(US Air Force, US Army, US Marines) A 2nd Lieutenant. / (US Navy, US Coast Guard) An Ensign.

(organic chemistry, IUPAC name) isoprene

The technical notion of sensitive dependence on initial conditions in chaos theory.

The yellow wood anemone.

plural of buttercup anemone

A non-serrated or unilaterally serrated table knife with a dull edge and rounded point, designed for spreading butter on a piece of bread without tearing it.

Of a collar, able to be buttoned down to the shirt, as over a necktie. / (idiomatic) Serious; staid; businesslike. / (idiomatic) Conservative; conventional; unimaginative.

A shirt with a button-down collar

A button on a corset.

(organic chemistry) An unsaturated hydrocarbon, CH₂=CH-CH=CH₂; it is obtained from petroleum and is used in the preparation of the synthetic rubber polybutadiene.