Simple

Synonyms: Straightforward, uncomplicated, effortless, manageable, unexacting, child's play, a five-finger exercise, as easy as falling off a log, as easy as ABC, a cinch, easy-peasy, a doddle, money for old rope, kids' stuff, a doss, duck soup, a bludge, a piece of old tackle, plain, intelligible, understandable, lucid, unambiguous, accessible, easy, uninvolved, painless, undemanding, elementary, plain sailing, nothing, as easy as pie, a piece of cake, a snip, no sweat, a pushover, money for jam, a breeze, a cakewalk, a snap, a snack, clear, clearly expressed, comprehensible, (words) of one syllable, coherent, direct, and user-friendly.

Synonyms: Basic, mere, pure, candid, honest, sincere, absolute, bald, naked, unadorned, unembellished, fundamental, sheer, pure and simple, frank, direct, plain, unqualified, stark, blunt, and unvarnished.

Synonyms: Plain, undecorated, unornamented, unelaborate, unostentatious, no-nonsense, modest, penny plain, honest, homespun, workaday, severe, austere, spare, muted, patternless, understated, clean, homestyle, unadorned, unembellished, without ornament/ornamentation, unpretentious, unfussy, basic, unsophisticated, without frills, homely, everyday, stark, spartan, chaste, bare, unpatterned, classic, uncluttered, restrained, and no-frills.

Synonyms: Unpretentious, ordinary, unassuming, honest-to-goodness, homely, humble, lowly, innocent, guileless, naive, gullible, cracker-barrel, unsophisticated, unaffected, natural, modest, wholesome, quiet, rustic, artless, childlike, ingenuous, inexperienced, and green.

Synonyms: Non-compound, uncompounded, unmixed, unalloyed, basic, elementary, non-complex, uncombined, unblended, pure, single, and fundamental.