Definition - weak, ineffective
Not only does our language have feckless and feck (which in this case means “worth, value”), but also lesser-known words such as feckful and feckly. Feck, which is Scottish in origin and most current use, as other meanings in addition to “worth,” including “the greater share,” “part, portion,” and “a number or quantity especially when large.”
The things I said gif that thou wald deny,
Meaning to wry the verity with wyles,
Lick where I laid, and pickle of that pye,
Thy knavery credence fra thee quite exyles,
Thy feckles folly all the aire defyles,
I find sa many faults, ilk ane ouer vther,
First I must tell thee all thy statelyy styles,
And syne bequeath thee to thy birken brother.
Fond flytter, shit shyter, bacon bytter, all defyl'd,
Blunt bleittar, paddock pricker, pudding eiter, perverse,
Hen plucker, closet mucker, house cucker, very vyld,
Tauny cheiks, I thinke thou speiks, with thy breeks, foul erse,
Woodtyk, hoodpyk, ay like to liue in lacke,
Flowre the pin scabbed skin, eat it in, that thou spake.
— Alexander Montgomerie, The flyting betwixt Montgomery and Polwart, 1621