1.  rustiness(n = noun.state) - the condition of being coated or clogged with rust;
is a kind of condition, status
Derived form adjective rusty₁

2.  rustiness(n = noun.cognition) - ineptitude or awkwardness as a consequence of age or lack of practice; "his rustiness showed when he was asked to speed up"
is a kind of awkwardness, clumsiness, ineptitude, ineptness, maladroitness, slowness
Derived form adjective rusty₃

   The quality or state of being rusty. [1913 Webster]

N  inactivity, inaction, inertness, obstinacy, lull, quiescence, rust, rustiness, idleness, remissness, sloth, indolence, indiligence, dawdling, ergophobia, otiosity, dullness, languor, segnity, segnitude, lentor, sluggishness, procrastination, torpor, torpidity, torpescence, stupor, somnolence, drowsiness, nodding, oscitation, oscitancy, pandiculation, hypnotism, lethargy, statuvolence heaviness, heavy eyelids, sleep, slumber, sound sleep, heavy sleep, balmy sleep, Morpheus, Somnus, coma, trance, ecstasis, dream, hibernation, nap, doze, snooze, siesta, wink of sleep, forty winks, snore, hypnology, dull work, pottering, relaxation, Castle of Indolence, lullaby, sedative, tranquilizer, hypnotic, sleeping pill, relaxant, anaesthetic, general anaesthetic, torpedo, idler, drone, droil, dawdle, mopus, do- little faineant, dummy, sleeping partner, afternoon farmer, truant, bummer, loafer, goldbrick, goldbicker, lounger, lazzarone, lubber, lubbard, slow coach (slow, ), opium eater, lotus eater, slug, lag, sluggard, slugabed, slumberer, dormouse, marmot, waiter on Providence, fruges consumere natus, inactive, motionless, unoccupied, unbusied, indolent, lazy, slothful, idle, lusk, remiss, slack, inert, torpid, sluggish, otiose, languid, supine, heavy, dull, leaden, lumpish, exanimate, soulless, listless, drony, dronish, lazy as Ludlam's dog, dilatory, laggard, lagging, slow, rusty, flagging, lackadaisical, maudlin, fiddle-faddle, pottering, shilly-shally, sleeping asleep, fast asleep, dead asleep, sound asleep, in a sound sleep, sound as a top, dormant, comatose, in the arms of Morpheus, in the lap of Morpheus, sleepy, sleepful, dozy, drowsy, somnolent, torpescent, lethargic, lethargical, somnifacient, statuvolent, statuvolic, heavy, heavy with sleep, napping, somnific, somniferous, soporous, soporific, soporiferous, hypnotic, balmy, dreamy, unawakened, unawakened, sedative, inactively, at leisure, the eyes begin to draw straws, bankrupt of life yet prodigal of ease, better 50 years of Europe than a cycle of Cathay, idly busy rolls their world away, the mystery of folded sleep, the timely dew of sleep, thou driftest gently down the tides of sleep, tired Nature's sweet restorer, balmy sleep.