If you look at the wheat plant, you can see that ear looks like a head standing on a long neck (stem).
This is the part of the cereal plant which is collected during harvest. Harvesting cereal literally means cutting off the long necks of the wheat plants and collecting the heads of the wheat plants, the ears.
The wheat is basically "slaughtered".
In Serbian the word for ear of corn is "klas". It comes from Proto-Slavic *kolsъ. which also means ear of corn and it has cognates in all Slavic languages.
The Proto-Slavic word *kolsъ does not have any proposed deeper etymology. So I would like to propose one.
As we have seen, harvesting of the wheat involves cutting the necks of wheat plants, slaughtering of the wheat plants. In Serbian the word for "to slaughter" is "klati". So if you wanted to explain to someone how to harvest wheat, you could just say "kolje se" meaning "it is slaughtered". This would be sufficient. Anyone who have ever slaughtered animals would know exactly what then needed to do. Pick up the head (ear) of the wheat plant and cut its neck. What you are left holding in your hand is the ear of corn, "klas" = "kolje se" = "what is slaughtered"...
According to the Russian etymological dictionary, the word klas could be cognate with Albanian "kall" meaning to "to stick (on, into), put (up), thrust, instigate" which is cognate with "klati" meaning to cut, to slaughter. The same entry in the Russian etymological dictionary mentions the Latin word "collum" which means neck, throat, upper stem of a plant, (symbolically) servitude, and says that it is not the cognate. But I believe that it is. This again could be coming from the same root "klati" meaning "to slaughter". The word "koljem" means "I slaughter" or "what I slaughter, where I slaughter". So "collum" = "koljem" = "what I cut" = neck, upper stem of a plant...
I like the gruesome bluntness of this... It is almost poetic... And it is ancient.
Is it possible that this word comes from the time when agriculture was being spread through Europe. From the time when the future nouns used today for parts of the wheat plants were still being formed from verbs explaining what to do with these plant parts.
But then there is Norse word "klase" meaning "a bunch, a cluster". How old is this word? Is it possible that this is the root of the Slavic word "klas", meaning "a bunch, a cluster of seeds"? Or is it the other way round? Did the Norse word "klase" meaning "a bunch, a cluster" come from the Slavic word "klas" which at that time already meant "a bunch, a cluster of seeds". These two words are definitely related.
We also have the Latin word "classis" which means "any one of the five divisions into which Servius Tullius divided the Roman citizenry, the armed forces, fleet, a group, rank, or class", but which is said to be derived from Proto-Indo-European *kelh₁- (“to call, shout”)...But again is it possible that this word was derived from the word "klas" meaning "bunch, cluster of seeds"?
So what do you think?