1.  sameness(n = noun.attribute) - the quality of being alike; "sameness of purpose kept them together"
is a kind of quality
has particulars: identicalness, identity, indistinguishability, similarity, equality
Antonym: difference
Derived form adjective same₂

2.  sameness(n = noun.attribute) humdrum, monotony - the quality of wearisome constancy, routine, and lack of variety; "he had never grown accustomed to the monotony of his work"; "he was sick of the humdrum of his fellow prisoners"; "he hated the sameness of the food the college served"
is a kind of unvariedness
Derived form adjective same₄

1.  The state of being the same; identity; absence of difference; near resemblance; correspondence; similarity; as, a sameness of person, of manner, of sound, of appearance, and the like. Bp. Horsley. [1913 Webster]

2.  Hence, want of variety; tedious monotony. [1913 Webster]

N  identity, sameness, coincidence, coalescence, convertibility, equality, selfness, self, oneself, identification, monotony, tautology, facsimile, homoousia: alter ego, ipsissima verba, same, self, very, one and the same, very thing, actual thing, real McCoy, no other, one and only, in the flesh, identical, self, ilk, the same, selfsame, one and the same, homoousian, coincide, coalescent, coalescing, indistinguishable, one, equivalent, tweedle dee and tweedle dum, much the same, of a muchness, unaltered, identically, on all fours.

N  similarity, resemblance, likeness, similitude, semblance, affinity, approximation, parallelism, agreement, analogy, analogicalness, correspondence, homoiousia, parity, connaturalness, connaturality, brotherhood, family likeness, alliteration, rhyme, pun, repetition, sameness, uniformity, isogamy, analogue, the like, match, pendant, fellow companion, pair, mate, twin, double, counterpart, brother, sister, one's second self, alter ego, chip of the old block, par nobile fratrum, Arcades ambo, birds of a feather, et hoc genus omne, gens de meme famille, parallel, simile, type, image, photograph, close resemblance, striking resemblance, speaking resemblance, faithful likeness, faithful resemblance, similar, resembling, like, alike, twin, analogous, analogical, parallel, of a piece, such as, so, homoiousian, connatural, congener, allied to, akin to, approximate, much the same, near, close, something like, sort of, in the ballpark, such like, a show of, mock, pseudo, simulating, representing, exact, lifelike, faithful, true to nature, true to life, the very image, the very picture of, for all the world like, comme deux gouttes d'eau, as like as two peas in a pod, as like as it can stare, instar omnium, cast in the same mold, ridiculously like, as if, so to speak, as it were, as if it were, quasi, just as, veluti in speculum, et sic de similibus, tel maitre tel valet, tel pere tel fils, like master, like servant, like father, like son, the fruit doesn't fall far from the tree, a chip off the old block.