Antonyms of adj arciform

1 sense of arciform

Sense 1
arced, arched, arching, arciform, arcuate, bowed -- (forming or resembling an arch; "an arched ceiling")

INDIRECT (VIA curved) -> straight -- (free from curves or angles; "a straight line")

Similarity of adj arciform

1 sense of arciform

Sense 1
arced, arched, arching, arciform, arcuate, bowed -- (forming or resembling an arch; "an arched ceiling")
       => curved (vs. straight), curving -- (having or marked by a curve or smoothly rounded bend; "the curved tusks of a walrus"; "his curved lips suggested a smile but his eyes were hard")