The best replacement for diagonals is sides.

The best alternatives to diagonals are rated as following:
★★★★★  sides

Your alternative for diagonals is not listed? Suggest!
Speaking about diagonals, one probably shouldn't forget about rectangles.

Other search terms related to diagonals and their ratings are:
★★★★★ rectangles
★★★★ hexagon
quadrilaterals
being a rhombus
You have in mind a companion for diagonals and it is not yet here? Propose!



Google Trends

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diagonals
sides