(n.) The degree of combining power of an atom (or radical) as shown by the number of atoms of hydrogen (or of other monads, as chlorine, sodium, etc.) with which it will combine, or for which it can be substituted, or with which it can be compared; thus, an atom of hydrogen is a monad, and has a valence of one; the atoms of oxygen, nitrogen, and carbon are respectively dyads, triads, and tetrads, and have a valence respectively of two, three, and four.

abiding accordant active age-long aged ageless alike ancient antique ardent articulated assiduous atom atomic mass atomic number atomic weight automatic balanced beaten catenated ceaseless changeless chattering chronic clinging close coeternal colorfast committed compliant concatenated confirmed conforming connected conscientious consistent consonant continual continued continuing continuous correspondent cyclical dateless dedicated deep-dyed delicate dependable determined devoted devout diligent direct diuturnal dogged double-dyed durable duteous dutiful dyed-in-the-wool endless enduring equable equal eternal eterne even ever-being ever-durable ever-during evergreen everlasting everliving exact express fadeless faithful fast featureless fine firm fixed flat flinty frequent frozen gapless habitual hackneyed hardy homogeneous immediate immemorial immobile immovable immutable inalterable incessant incommutable inconvertible indefatigable indefeasible indelible indestructible indomitable industrious inerrable inerrant inert infallible infinite inflexible ingrain ingrained insistent insusceptible of change intact interminable intransient intransmutable invariable inveterate invincible inviolate irretrievable irreversible irrevocable joined jointless lasting level liege linked long-lasting long-lived long-standing long-term longeval longevous loyal machine gun macrobiotic marble-constant mathematical measured mechanical methodic methodical meticulous micrometrically precise microscopic mindful monolithic monotonous never-ceasing never-ending never-tiring nice noble nonreturnable nonreversible nonstop nonterminating nonterminous observant obstinate of a piece of long duration of long standing olamic ordered orderly oscillating patient patient as Job perdurable perduring perennial periodic permanent perpetual perseverant persevering persistent persisting pertinacious pinpoint plodding plugging practicing precise preoccupied pulsating punctilious punctual quantum quiescent rapid rapt recurrent recurring refined regardful regular regular as clockwork relentless religious religiously exact remaining repeated repetitive resolute reverseless rigid rigorous robotlike round-the-clock routine running scientific scientifically exact scrupulous seamless sedulous sempervirent sempiternal serried set settled severe single-minded sleepless slogging smooth solid sot square stabile stable staccato static stationary staunch staying steadfast steady steely stereotyped straight strict stubborn stuttering subtle sustained