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