Why does Business read like busyness?

This is a bit weird, but the word business reads like busy-ness, but it sounds like biz-ness.

• Why is that?
• What happened to the i?

Solution 1:

The reason business looks like busy + ness is that that is precisely what it is; a noun formed from the adjective busy by adding the suffix –ness.

But this formation happened a long time ago. The word is found (spelled bisignisse) in Old English. Now, consider how Old English sounds very different to Modern English (or if you aren't already familiar with this, then consider that the first three lines of Beowulf are the sentence "Hwæt! We Gardena in geardagum þeodcyninga þrym gefrunon hu ða æþelingas ellen fremedon.") and that many words have changed in the meantime.

In the course of these changes, people slipped over the middle vowel, much like some people would pronounce "did you" as "didja".

This became so common, that it became the normal pronunciation. Compare how forecastle became fo'c's'le.

While some people spelled the word so as to reflect this (busnes, bisnies, bisnes are all examples found between the 15th and 17th century) and some used the apostrophe to reflect both the pronunciation and the earlier origin (buis'ness), many spellings continued to include the elided i or y, and eventually business became what is now considered the sole correct spelling.

There are dialects that include the middle vowel. In the case of some Irish dialects (most pronounce it as two syllables like most other dialects), the influence of the guta cúnta (a pronunciation rule in the Irish language where a "helper vowel" is sometimes inserted) means that some words are pronounced with an extra /ə/ between consonants, such as film being prounounced /fɪləm/ rather than /fɪlm/ as in most English dialects. As such, the general tendency toward eliding the vowel was more likely to be resisted. Alternatively, it could even be that both happened—the vowel was elided as with most English dialects, and then put back in again as with film.

Solution 2:

That's a pronunciation issue more than anything else. People now pronounce it 'bizness' in some parts of the world, but a lot of the UK and Ireland would still say 'biz-eh-ness', pronouncing the middle syllable.