1. Of or pertaining to right lines or angles 
2. Of or pertaining to orthography, or right spelling; also, correct in spelling; as, orthographical rules; the letter was orthographic

Encyclopedia: Orthographical

• drop cloth
• drop curtain
• drop down
• drop earring
• drop goal
• drop hammer
• drop in
• drop keel
• drop like flies
• drop off
• drop one's serve
• drop open
• drop press
• drop scone
• drop shot
• drop the ball
• drop zone
• drop-dead
• drop-down menu
• drop-leaf
• drop-leaf table
• drop-off charge
• dropforge
• dropkick
• dropkicker