You can think of a cleat as one small hard piece bolted onto a much bigger surface, put there so that something else will not slide. The piece is never the main thing. A rope, a shoe, a loose board — that is what matters, and the cleat is the little lump that keeps it where it should be. Once you hold that picture, the boat fitting, the bumps under a sports shoe and the strip screwed across a door are all the same idea in different places.
The supplied Wiktionary entry traces cleat to Middle English clete and Old English *cleat, a block or wedge, from a root meaning a firm lump, and names German Kloss (a clump) as a cognate. That old lump is still visible in every modern use: a cleat is a hard little mass fixed onto something bigger.
資料裡的 Wiktionary 條目說 cleat 來自中古英語 clete、古英語 *clēat（塊、楔），更早的字根有「結成一團的硬塊」的意思，並列出德文 Kloß（麵團塊）為同源詞。那個「硬塊」到今天還看得見：cleat 就是被固定在大東西上的一小團硬物。
Wiktionary entry supplied in this packet (source_ref kaikki:3f6f69a190036ae4:632903318)
Three branches
船上的繫繩件
這一家是核心畫面最直接的樣子。一小塊硬東西裝在碼頭或甲板上，兩頭伸出角，繩子繞上去就跑不掉。要走的時候一拉就鬆，比打結方便，所以港口幾乎都用它。
noun · C1
A small metal or wooden part with two short arms, fixed to a boat or to a dock, that a rope is wound around so that the rope holds firm and can still be let go quickly.
繫纜樁
鞋底的抓地
一樣是「釘上去的小硬塊」，只是這次裝在鞋底，而且一次裝很多顆。要擋住的不是繩子，是整個人：濕草地上腳會滑，這些小凸起往下咬住地面，人就站得住。
noun · B2
One of the short pieces of rubber, plastic or metal fixed to the bottom of a sports shoe, so that the shoe grips soft ground and the player does not slip. It is usually used in the plural.
鞋底防滑釘
釘在板子上的橫條
這一家最接近這個字最老的意思，也就是一塊木頭或楔子。硬塊在這裡被拉長成一條，橫著壓在板子上，管的是板子自己不要彎、不要散。
noun · C1
A narrow strip or block of wood or metal fixed across a surface, usually at right angles to it, to make it stronger, to stop it bending or twisting, to hold another piece in place, or to give feet a grip on a slope.
橫條（補強條）