From this original meaning the word has enlarged until now it means to tease, to trouble, to harass with importunity or with care or anxiety.

In other words it is _undue_ care, _needless_ anxiety, _unnecessary_ brooding, _fretting_ thought.
What a wonderful picture the original source of the word suggests of the latter-day meaning.

Worry takes our manhood, womanhood, our high ambitions, our laudable endeavors, our daily lives, _by the throat_, and strangles, chokes, bites, tears, shakes them, hanging on like a wolf, a weasel, or a bull-dog, sucking out our life-blood, draining our energies, our hopes, our aims, our noble desires, and leaving us torn, empty, shaken, useless, bloodless, hopeless, and despairing.

It is the nightmare of life that rides us to discomfort, wretchedness, despair, and to that death-in-life that is no life at all.

It is the vampire that sucks out the good of us and leaves us like the rind of a squeezed-out orange; it is the cooking-process that extracts and wastes all the nutritious juices of the meat and leaves nothing but the useless and tasteless fibre.
Worry is a worse thief than the burglar or highwayman.