An onion is basically one; so is the glass pear that lights up bright ideas.

Shows you how heavy a package will be. Climbing a mountain or swimming the sea. Altering maps for the distance you see. Lined up in music, a vocal degree. Each dragon and serpent, covered in me. Still no idea? Full acrostic, the alt key.

It can blend, it can twist, it turns with a spin, Shaping the texture or the track that you're in. It controls your dough, or the beats on the floor, Just one single word, capable of much more.

I stretch across the gap where two sides cannot meet, giving you a path beneath your feet.

I am round, I am toothed, Old machines have me uncouth. I grind, I lift, I make things go, What am I? Do you know?