undo

Everyday

1. To undo is to turn something back to how it was before. tree →
2. To undo is to open something that is tied or fastened, like a knot, a button or a zip. tree →
3. On a computer, Undo cancels the last thing you did. tree →

In the lessons

one operation reverses another: dividing undoes multiplying, adding undoes taking away; to find a starting amount, undo each change; phrases: «undo a knot», «undo a button», «press undo»

Examples

• Dividing undoes multiplying: 3 × 4 = 12, so 12 ÷ 3 = 4. tree →
• Adding 5 undoes taking 5 away. tree →
• To find the start, undo each change. tree →
• Can you undo this knot in my shoelace? tree →
• Undo your top button if you feel hot. tree →
• Press undo to bring back the deleted word. tree →
• You cannot undo a mean word once it is said. tree →
• Subtracting 7 undoes adding 7. tree →
• But he could not undo the string. tree →

Note

Past: undid; past participle: undone. Use the undoing operation to check an answer or to find a starting amount. Pairs that undo each other: + and −, × and ÷.

In Jewish tradition

In Isaiah it means to loosen a yoke or ropes that bind an oppressed person.

Interpretation. Isaiah says the fast God wants is freeing the oppressed, not only going hungry. It is read aloud on Yom Kippur morning as a call to justice and kindness.

Examples

• Is not this the fast that I have chosen? to loose the fetters of wickedness, to undo the bands of the yoke, and to let the oppressed go free, and that ye break every yoke? (Prophets ISA.58.6, JPS 1917) tree →

Note

Past: undid; past participle: undone. Use the undoing operation to check an answer or to find a starting amount. Pairs that undo each other: + and −, × and ÷.