Synonyms for Weakness:

n.

gap, disturbance, flaw, the vapors, virtue, deficiency, good, fault, lapse, instability, vice, indecision, defect. unsubstantiality, decadence, weakliness, overindulge, unsoundness, epicurean, indulgence, strong, insubstantiality, Delicateness, sybaritic, fragileness, puniness, for fun, fun-loving, self-indulgence, extravagance. help, foible, shortcoming, weak point, better. like, partiality, relish, preference, taste, fondness, appetite. condition (noun)
infirmity.
defect, proneness (noun)
fondness, shortcoming, faintness, impotence, appetite, indecision, feebleness, powerlessness, decrepitude, irresolution, fault, debility, prostration, inclination, lapse, liking, failing, instability, infirmity, invalidity, deficiency, fragility, taste, flaw, vice, enervation, imperfection, frailty, senility, delicacy, gap.
fatigue (noun)
faintness.
feebleness (noun)
flimsiness, decrepitude, feebleness, Sickliness, softness, debilitation, fragility, faintness, powerlessness, infirmity, ricketiness, frailness, ailment.
impotence (noun)
inability, disability, incapability, handicap, incompetence, inadequacy.
inclination (noun)
hunger, bent, liking, fault, tendency, inclination.
ineffectuality (noun)
incapability.
instability (noun)
capriciousness, changeability, unsureness, fickleness.
irresolution (noun)
insipidity, uncertainty, inconsistency, unsureness, ambivalence, indecisiveness, double-mindedness, capriciousness, irresolution, shyness, yellowness, spinelessness, tentativeness, vacillation, shiftiness, unwillingness, changeability, volatility, wateriness, impulsiveness, halfheartedness, fickleness, hesitance.
tastelessness (noun)
banality, staleness, plainness, unsavoriness, vapidity, flatness, mildness, tastelessness, blandness.
weakness (noun)
failing, frailty, impotence, helplessness, impuissance, debility, anemia.
weariness (noun)
ennui, exhaustion, boredom, blues, over-weariness, listlessness, drowsiness, flaccidity, depression, sleepiness, cheerlessness, weariness, tiredness, fatigue, footsoreness, droopiness, tedium, apathy.

Other synonyms:

Delicateness, Achilles' Heel, fragileness, inclination, unsoundness, decadence, epicurean, self-indulgence, imperfection, weak point, sybaritic, unsubstantiality, insubstantiality, fun-loving, weakliness, puniness, deficiency. fault, defect, overindulge, extravagance, relish, foible. delicacy, fondness, preference, indulgence. appetite. partiality. effeminacy
femininity.
fault
shortcoming.
inconstancy
instability.
old age
senility.

Usage examples for weakness

  1. It is not the kind of weakness I have seen in him. – The Claverings by Anthony Trollope
  2. He was angry with himself for what seemed to him a selfish weakness – A Millionaire of Rough-and-Ready by Bret Harte
  3. " This is all a weakness I said to myself, after my friend had left, making an effort to throw off the uncomfortable feeling. – Home Scenes, and Home Influence A Series of Tales and Sketches by T. S. Arthur