About 90% of Spanish words derive from Latin, 8% from Arabic, and the rest from other sources.
Most words beginning with 'al-' are Arabic, as are most words having no clear link to Latin. Persons familiar with Italian or French will often recognize this in Spanish words unrelated to their counterparts in those languages.
An example is 'hermano' (brother) which is totally unlike 'frère' or 'fratello'.
Hermano < Lat. germanus < Lat. germen < P.I.E (proto Indo-European) gen- (nothing to do with the goths). Cognates: French - germain ; Portuguese - irmão ; Catalan - germà
Some words are contractions or corruptions of older compound terms. Here are two examples. 'Semana' ('week', It. 'settemana'), is short for 'siete mañanas' or 'seven mornings'. 'Como' ('how') derives from Latin 'quo modo', 'in which manner'. Many English-speaking Spanish students struggle with 'ser' and 'estar', which both translate as 'to be' but which differ greatly in Spanish meaning. Their origins give a clue to meaning. 'Ser' derives from Latin 'esse', to be or have the ESSEnce of. 'Estar' derives from 'stare', to STAnd or be in a STAte. The latter is subject to change; the former is not.
This means that Spanish, like other Indo-European languages, through its oldest to its modern form, has steadily depended less on inflections (suffixes on nouns, adjectives etc.) to demonstrate syntactical relationships and more on word order and prepositions.
This is one of the most predictable patterns in the development of Spanish and the first written record of it is from 863 when the Latin 'Forticius' was written as 'Ortiço.' The h- was originally pronounced as an aspirate (i.e.
The Spanish educational system, and later the Real Academia Española, with their demand that all consonants of a word be pronounced, steadily drove most simplified forms from existence.
From Antiquity through the 17th century, from Pindar to Sir Thomas Browne, etymology has been a form of witty wordplay, in which the supposed origins of words were mythologized to satisfy contemporary requirements, much as myths were formed to explain archaic rituals that were no longer comprehensible.
Although, it must be said, many of Nietzsche's etymologies are wrong, the strategy has gained popularity in the 20th century, with philosophers such as Jacques Derrida using etymologies to indicate former meanings of words with view to decentring the "violent hierarchies" of Western metaphysics.