Flotsam and jetsam
Ships' goods which are lost at sea. Also used figuratively in non-nautical contexts to means odds and ends, bits and pieces.
Flotsam and jetsam are rarely seen apart nowadays although the words, in a variety of spellings, have separate meanings and were frequently used independently in the 17th century. John Cowell, in his 1607 publication The interpreter: or booke containing the signification of words [what we would now prosaically call a dictionary] wrote of "Flotsen alias (Flotzam)". In 1570 Boys' Sandwich [that's a book, of course, not a snack], 1570, we find:
"[At a special brother-hood held at Sandwich: Decreed to give the Lord Warden of free gift and not otherwise the third part] of all wrecks and fyndalls floating and the half of all wrecks and fyndalls jottsome, viz. dryuen to the londe yshore."
The easiest way to remember which is which; flotsam floats.
There's a simple mnemonic that helps distinguish flotsam from jetsam. Flotsam (or floatsome) are those items which are floating as a consequence of the action of the sea. Jetsam are those which have been jettisoned by a ship's crew (although that may float too of course).
Whenever flotsam and jetsam meet for a drink they always reminisce about the family's long-lost triplet - lagan. That's the word for goods or wreckage that lie at the bottom of the sea and, like Gummo and Zeppo Marx, it rarely gets a mention.
Around the turn of the 17th century though, lagan was still in vogue. The 1591 record - Articles concerning the admiralty of England, and the iurisdiction thereof stated:
"Any ship, yron, leade, or other goods floating or lying under the water or in the depth, of which there is no possessor or owner, which commonly are called Flotzon, Jetson, and Lagan."
The English royal household rarely missed a trick where money was concerned and by 1622 it was said that those watery items described above as having 'no owner' now became property of the King. Robert Callis wrote [citing Coke] "Flotsan, Jetsan and Lagan are goods on or in the Sea, and ... they belong to the King."
Flotsam and jetsam formed an alliance of their own and allowed lagan to sink out of trace in the early 19th century. Sir Walter Scott, in his Diary, 1848 (later printed by John Lockhart) mentions this:
"The goods and chattles of the inhabitants are all said to savour of Flotsome and Jetsome."
See also - phrases coined by Sir Walter Scott.