尚未
shàngwèi · HSK 7
as yet
⏳ 尚 still + 未 not-yet = still-not = hasn't happened so far
尚 carries the sense of still or yet, and 未 is the classical not-yet negator (the same 未 in 未来 future). Stacked, they mean something has not occurred up to now: as yet, heretofore.
尚 — 八 (eight/divide) over 向 (window/direction)
Originally depicted vapor or breath rising and dispersing upward from an opening, suggesting elevation and what is above. From this came the meanings 'still,' 'yet,' and 'to esteem' — what one looks up to. The modern senses of 'esteem' and 'still/yet' both stem from this upward orientation.
未 — tree 木 with extra short top stroke
未 originally pictured a tree with luxuriant new branches at the top, suggesting tender shoots not yet matured. From this 'not yet ripe' image it came to mean 'not yet' or 'have not.' It is also the 8th Earthly Branch, used in the traditional sexagenary cycle.