(idiomatic) To undertake a pointless venture, one that is redundant, unnecessary, superfluous, or highly uneconomical.

(physics, chemistry) Any atom which has a single valence electron in a shell well outside any other electrons in the aton; approximates the hydrogen atom.

(idiomatic) To scold, to rebuke, often by yelling.

At this moment; right now. / (dated) At that time; then.

radio interference caused by pulses of electromagnetic radiation in the atmosphere as the result of lightning and other events (both natural and man-made)

In an athletic manner.

The weighted average of the atomic masses of the naturally occurring isotopes of an element.

plural of athletic supporter

At an angle from the vertical or horizontal.

At an angle from the vertical or horizontal; at the point of falling over. / Tilting or as if tilting (charging with a lance, like a knight on horseback in a joust).