Sustancia capaz de formar iones de hidrógeno cuando se disuelve en agua. (es)
Een substantie die waterstofionen produceert wanneer het in water wordt opgelost. (nl)
溶解於水中時,能夠形成氫離子的一種物質。 (zh-hant)
Large class of electrolytic chemical substances that are capable of donating a hydrogen atom. Acids are classified as strong or weak depending on the concentration of hydrogen ion produced on ionization. Acids exhibit one or more of the following characteristics: has a sour or sharp taste; forms an aqueous solution with a pH of less than 7.0; turns litmus dye red; reacts with bases and some metals to form salts; or reacts with a metal carbonate to release carbon dioxide. (en)