The Spanish verb 'desechar' (meaning 'to discard' or 'reject') comes from the Latin word 'disiectare', meaning 'to scatter' or 'throw apart'. This Latin word was formed by combining two elements: the prefix 'dis-' (meaning 'apart' or 'in different directions') and 'iactare' (meaning 'to throw' repeatedly). The evolution from 'disiectare' to 'desechar' involved phonetic changes typical in the development from Latin to Spanish, where the 'i' in 'dis-' became 'e', and the '-ct-' cluster simplified to '-ch-'.

The semantic development from 'to scatter/throw apart' to 'to discard/reject' is quite logical - when you discard something, you are metaphorically throwing it away or casting it aside.

Some related Spanish words include 'echar' (to throw, to cast), which comes from the same Latin root 'iactare'. You can see how 'desechar' is essentially 'des-' + 'echar', meaning to throw away or cast aside. Another related word is 'echar de menos' (to miss someone/something), which literally meant 'to throw less' but evolved to mean 'to notice something's absence'.

English words related to 'desechar' through the Latin 'iactare' include 'eject' (to throw out), 'inject' (to throw in), 'project' (to throw forward), and 'jet' (which originally referred to something thrown or shot forth). All these words preserve the basic meaning of throwing or casting something in different directions. The English prefix 'dis-' seen in words like 'discard' is also related to the same Latin prefix found in 'desechar'.