Base's chemical opposite

Editorially verified for the Oct 19, 2026

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A pH scale showing acidic substances on one side and basic substances on the other.

Clue explained

An acid is the chemical opposite of a base, the pairing used in basic chemistry. In water, acids typically have a pH below 7, while bases have a pH above 7. Vinegar and citrus juice are familiar examples of acidic substances.

Clue type:
Definition

USA Today Crossword

This clue's Monday, October 19, 2026 appearance

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Across

  1. 1Foam shoe with 13 holes
  2. 5Strikebreakers, sometimes
  3. 10Become taller
  4. 14Very, very
  5. 15Geoje Island's region
  6. 16Currency in Bulgaria, as of 2026
  7. 17"Expect to be reprimanded soon"
  8. 20Match, like song BPMs
  9. 21Takes home the gold
  10. 22"Drove my Chevy to the ___, but the ___ was dry"
  11. 25Sun Devils' sch.
  12. 27Skewered snack
  13. 31Way out
  14. 32Most NASCAR racetrack shapes
  15. 34Something topped with cilantro, perhaps
  16. 35Ride-hailing app tech
  17. 36Distressed
  18. 38Baby goat
  19. 39Protruding navel
  20. 41Cure
  21. 43Eat it up!
  22. 47"The Handmaid's ___"
  23. 49Where the sand meets the sea
  24. 50Tempo
  25. 53Large coffee container
  26. 54Gymnast's garment
  27. 56Salonga who provided the singing voice for Jasmine
  28. 57Extent
  29. 59Faux ___
  30. 60Apple tablets
  31. 62Settle matters once and for all
  32. 65"Aha moment" output
  33. 66Cobra pose, for one
  34. 67Sinigang vegetable
  35. 68Slippery fish
  36. 69Lettuce-grabbing tool
  37. 70Used to be

Down

  1. 1Shy, but not really
  2. 2Letter after pi
  3. 3Buckeyes' sch.
  4. 4Period costume piece in "Six" or "Hamilton"
  5. 5Sunscreen target
  6. 6Like a bowl's shape
  7. 7Dog's sound
  8. 8Old English epic poem whose title character fights Grendel
  9. 9Red outfit at a wedding
  10. 10"On your mark, ___, go!"
  11. 11Compete in a 10K
  12. 12Gold, in Spanish
  13. 13:O reaction, on Facebook
  14. 18Visine drop target
  15. 19Tattoo liquid
  16. 22One of a tripod's three
  17. 23Trade show
  18. 24Story-heavy video game genre
  19. 26Plopped on a beanbag
  20. 28Cold dessert named after a state
  21. 29Base's chemical opposite
  22. 30Out-of-___ experience
  23. 32End of an ultimatum
  24. 33Banzai Pipeline rider
  25. 36Douglas ___
  26. 37Feline zodiac sign
  27. 405-5, e.g.
  28. 42Tool for a spill
  29. 44"Fingers crossed!"
  30. 45"I prefer something different"
  31. 46Getting a clean slate?
  32. 47Bum-bum
  33. 48Place with claw games
  34. 51Fragrant evergreens
  35. 522010 Emma Stone comedy
  36. 54"___ me see . . ."
  37. 55___ de los Reyes Magos
  38. 58Spherical veggies
  39. 61Snow-clearing vehicle
  40. 63Headwear doffed or tipped
  41. 64___ational ___cademy of ___ciences

The answer to “Base's chemical opposite” in the USA Today crossword is ACID — a 4-letter word. It most recently appeared in the USA Today crossword on October 19, 2026, a Monday puzzle, at 29-Down. Below you'll find why that fill fits, every other answer we've recorded for this clue, and links into the puzzle it came from.

“Base's chemical opposite” answer

ACID (4 letters)

Reveal the solution one letter at a time with the tiles above if you'd rather nudge yourself toward it than see the whole word at once. Just want it outright? The answer is ACID.

What does ACID mean?

Reading the plain dictionary sense of ACID is often the fastest way to see why it answers this clue.

(noun)

  • a substance with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals; typically, a corrosive or sour-tasting liquid of this kind
  • a molecule or other species which can donate a proton or accept an electron pair in reactions
  • the drug LSD

When else has “Base's chemical opposite” appeared?

USA Today reuses clues across dates, sometimes with a different answer depending on the grid. Here's where this exact clue has shown up, and what the answer was each time — handy when you're checking whether today's fill is the only one.

October 19, 2026 (most recent) → ACID. We haven't indexed another appearance of this exact clue yet.

Frequently asked questions

What is the answer to “Base's chemical opposite”?

The answer is ACID, a 4-letter word. It most recently appeared in the USA Today crossword on October 19, 2026.

How many letters is the answer to “Base's chemical opposite”?

4 letters: ACID.

When did this clue appear?

Most recently in the USA Today crossword on October 19, 2026 (a Monday puzzle), at 29-Down.

Can “Base's chemical opposite” have a different answer?

Yes — USA Today sometimes reuses a clue with a different solution to fit the grid. The answers we've recorded for each date it appeared are listed above when available.

Where can I find the rest of this day's USA Today answers?

The full grid for October 19, 2026 is on the USA Today answers page, with every clue and answer from that puzzle.

USA Today Crossword is published by USA Today; WordHint is an independent site and is not affiliated with or endorsed by the publisher.

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