From acid +‎ -ic. Doublet of acidy.

• (US) IPA^(key): /əˈsɪ.dɪk/, enPR: əsĭdʹĭk

• Audio (Southern England):

  (file)

• Hyphenation: a‧cid‧ic

acidic (comparative more acidic, superlative most acidic)

1. Of or relating to acid; having the character of an acid.

   Synonym: acid

   an acidic solution

2. (physical chemistry) Having a pH less than 7, or being sour, or having the strength to neutralize alkalis, or turning a litmus paper red.

   Antonym: basic

   • 2015, Ramesh Gampat, Guyana: from Slavery to the Present, volume 2:

     The swampland is an extensive pegasse swamp, which is rich in organic matter and intensely acidic.

   • 2015 February 25, Kevin McElvaney, “Inside Indonesia's Ijen Volcano”, in The Atlantic‎^[1], archived from the original on 6 March 2016:

     Local workers hike up the side of the mountain and down into the crater at the top to harvest its sulfur—a byproduct of the gas that escapes from the volcano’s vents and collects near the shores of an acidic lake at the crater’s center. The chemical is used in industry worldwide, from making matchsticks to vulcanizing rubber, but Ijen’s sulfur goes mostly to local factories, which use it to bleach sugar.

3. (geology) Containing a high percentage of silica-bearing minerals.

   Antonym: basic

• “acidic”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.

acidic (not comparable)

1. acidic