基本上
jī běn shang · HSK 3
basically
基 (base) + 本 (root) + 上 (on top) = on the basic foundation = basically
基本 means 'foundation/basis' (base + root), and 上 here marks an abstract domain ('on the level of'). Together: 'on the basic level' → basically, on the whole.
本 — tree 木 + mark at base
本 is a pictograph of a tree (木) with a stroke at its base, marking the roots. From this 'root' meaning it extended to 'origin,' 'source,' and 'foundation.' In modern usage it also serves as a measure word for bound objects like books.
上 — horizontal line above a baseline
上 is an indicative character (指事): a short stroke placed above a longer reference line shows the concept of 'above' or 'up'. The earliest oracle-bone forms used two horizontal lines for this; the modern shape added a vertical stroke for clarity. The core meaning of 'upper, above, to ascend' has stayed stable for millennia.