Colloquial for ‘tidy,’ ‘very clean’ or ‘in good order.’ Sometimes spelled spic and span and/or hyphenated.
This phrase originated in the days of sailing ships. Spick and span originally meant ‘new’ and the evolution of this phrase parallels the development of the term ‘brand new’ or the archaic ‘fire new.’
The term for the nails which held a ship together was spick or spike. When a ship was brand new, the nailheads would gleam in a way that I would imagine was quite beautiful.
Span is derived from an old Norse word for sawdust or wood chips, spann-nyr, ‘new chips.’ The word span gives us our word spoon, as well. By about 1300, the term span new was common parlance for something (especially something made from wood) that was fresh and new and in perfect order.
The combined form of this expression seems to be from around the sixteenth century, and was likely inspired by the Dutch term spiksplinternieuw, meaning ‘nails and wood new.’ It was first used in Sir Thomas North’s translation of Plutarch’s Lives in 1579.
So, upon boarding a brand new ship for the first time, the nailheads gleaming and the sawdust and wood planings still roughening the deck, the owner and captain would be delighted to find it spick and span.
This is one of the many familiar phrases that originated back in the days of sailing ships. A few other familiar ones are "shipshape and Bristol fashion,” “learning the ropes” and “son of a gun.”
This expression has come under a bit of fire in recent years from well-meaning (but misguided) persons. The word spic (spelled like that) is a derogatory term for a person of Hispanic descent and this phrase has been incorrectly seen as somehow connected to that term.
This is also the name of a line of liquid cleaners (spelled with the variant Spic and Span) for floors, counters and windows. The Spic and Span products are manufactured by the Spic and Span company (who also make Cinch multi surface cleaner … good stuff if you have pet ferrets and/or cats).
References: Worldwide Words online: http://www.worldwidewords.org/qa/qa-spi5.htm
Classic FM Breakfast word of the day, http://www.abc.net.au/classic/breakfast/stories/s773478.htm
Spic and Span products website: Spicnspan.com