Plural of beta; either the second letter of the Greek alphabet, or test versions of software released early to find and fix problems.
From Greek 'beta,' borrowed into English via scientific and mathematical contexts. The software sense emerged in computer science in the 1970s-80s, using Greek letters to mark development stages.
When you download a 'beta' app, you're using terminology that goes straight back to ancient Greek alphabets—scientists chose Greek letters to sound objective and universal, and the practice stuck so hard that tech companies still use it today.
Complete word intelligence in one call. Free tier — 50 lookups/day.