Synonyms and related words :
accordant, alike, arrowlike, automatic, balanced, changeless, close, consistent, consonant, constant, continuous, correspondent, dead straight, delicate, direct, equable, equal, even, exact, express, faithful, fine, flat, homogeneous, horizontal, immediate, immutable, in a line, incommutable, inconvertible, indefeasible, inerrable, inerrant, inert, infallible, insusceptible of change, intransmutable, invariable, irretrievable, irreversible, irrevocable, lasting, level, lineal, linear, mathematical, measured, mechanical, methodic, micrometrically precise, microscopic, monolithic, nice, noble, nonreturnable, nonreversible, of a piece, one-way, ordered, orderly, permanent, persistent, pinpoint, precise, rectilineal, rectilinear, refined, regular, religious, religiously exact, reverseless, right, rigid, rigorous, robotlike, ruler-straight, scientific, scientifically exact, severe, smooth, square, stable, steadfast, steady, straight, straight-cut, straight-front, straight-side, straightaway, straightforward, straightway, streamlined, strict, subtle, systematic, TRUE, unalterable, unalterative, unaltered, unbending, unbent, unbowed, unbroken, unchangeable, unchanged, unchanging, uncurved, undeflectable, undeflected, undifferentiated, undistorted, undiversified, unerring, unidirectional, uniform, uninterrupted, unmodifiable, unremitting, unrestorable, unreturnable, unruffled, unsusceptible, unswerving, unturned, unvariable, unvaried, unvarying, upright, vertical