The spelling of "planks out" can be explained using the International Phonetic Alphabet (IPA). "Planks" is pronounced /plæŋks/, with the final /s/ indicating pluralization. "Out" is pronounced /aʊt/, with the vowel sound represented by /aʊ/ indicating a diphthong. Together, "planks out" is pronounced /plæŋks aʊt/. The phrase typically means to remove or detach planks, often in the context of a construction or woodworking project.
The phrase "planks out" does not have a specific etymology as it is not a commonly used phrase. However, if you are referring to the term "plankton" or "planktonic", that has a distinct origin. "Plankton" comes from the Greek word "planktós", meaning "wanderer" or "drifter". It was coined by German biologist Victor Hensen in 1887 to describe the diverse organisms that drift with oceanic currents, unable to swim against them. The use of "plankton" has since expanded to include microscopic organisms in both freshwater and marine environments.