Vertical
Perpendicular, Upright
な adjective, の adjective, noun
Something droops straight down, making it perfectly vertical. If we wanted to get fancy, we could even say it's perpendicular to the floor.
垂直 is a formal, precise word meaning vertical — perfectly up-and-down, at a 90-degree angle to the ground or another surface. You'll hear it in math, science, construction, or any situation where exact orientation matters, like 垂直の線 (a vertical line).
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
スマホが垂直に立っていてびっくりした。
I was surprised to see my smartphone standing perfectly upright.
この線は地面に対して垂直に引かれている。
This line is drawn perpendicular to the ground.
ボールは垂直に近い角度で落ちていきました。
The ball fell at an almost vertical angle.