Picture two rope ends. You do not tie them. You open each end into its separate strands, lay the two frayed ends into each other, and work the strands over and under until you cannot say where one rope stops and the other starts. Cut first, then join, and the join carries the same load as the rest. That single picture, an invisible join between two ends, runs under everything this word does.
From the word’s history
Wiktionary traces splice to Middle Dutch splissen, a relative of splitten, to split. The Dutch word first named only the fraying of a rope's ends, then came to cover the whole job of fraying and retying. That is how a word from the split family ended up meaning join, and it is why the core picture still starts with cutting.
Wiktionary 說 splice 大約一五二五年從中古荷蘭語 splissen 借來，和 splitten（劈開）同源。荷蘭語原本只指把繩頭拆散，後來把「拆散再編回去」整件事都包進去。所以一個從「劈開」那一家出來的字，最後變成「接起來」；也因此這個核心畫面永遠是先剪、再接。
Wiktionary entry for splice, packet evidence source_ref kaikki:3f6f69a190036ae4:666443113 — etymology_text describing Middle Dutch splissen, akin to splitten, and the development from split to join.
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