The only free and comprehensive online etymological dictionary of the Spanish language
local (1) (Adjective) "local"

Borrowed from Latin localis 'id.,' from locus "place" (see luego). The native word from localis is lugar.
local (2) m. (Noun) "nearby location" Often with a sense of being closed to visitors.

An adjectival from local (1).
loco (Adjective) "crazy"

12th cent. From a pre-form *laucu. Traditionally argued following Corominas (1991) to be from Arabic. More precisely, according to Corriente (1999), to be from Andalusian Arabic lawqa "foolish."

Romance: Western Vulgar Latin: Portuguese louco
locura f. (Noun) "insanity," "madness"

12th cent. From loco and -ura, an abstract noun-forming suffix.
-logía Suffix indicating a study or science.

Borrowed from Latin -logia 'id.,' itself borrowed from Ancient Greek -λογία (logía) 'id.' A compound of λόγος ‎(lógos) "explanation" (see -logo) and an abstract noun-forming suffix -ίᾱ ‎(-ía).
-logo Affix indicating study, specialization, word, or speech.

Borrowed from Latin -logus 'id.,' itself borred from Ancient Greek λόγος (lógos) "word," "speech," "explanation." Derived from λέγειν (légein) "to collect," "to arrange." From Proto-Indo-European *leǵ- "to collect."

Italic: Latin legere "to collect" (see Spanish leer)

Indo-European: Albanian: mb-ledh "to collect"
Londres m. (Noun) "London"

Of unknown origin but indisputably borrowed from another language. The original stem was *lond-.

Portuguese Londres is feminine.
lucha f. (Noun) "fight;" "wrestle"

13th cent. From Latin lucta 'id.,' derived from luctari "to wrestle" (see luchar).

Romance: Western Vulgar Latin: Asturian llucha, Portuguese luta, Galician loita, French lutte, Italian lotta; Eastern Vulgar Latin: Aromanian ljuftã, Romanian luptă
luchar (Verb) "to fight;" "to wrestle"

13th cent. From Latin luctare 'id.,' originally luctari. From Proto-Italic *lukto- "to wrestle," but originally "bent." From Proto-Indo-European *leu̯g- "to bend."

Romance: Western Vulgar Latin: Asturian lluchar, Portuguese lutar, Galician loitar, Catalan lluitar, French lutter, Italian lottar; Eastern Vulgar Latin: Romanian lupta

Indo-European: Celtic: Old Irish foloing "support," Middle Welsh ellwng- "to set free;" Germanic: Gothic ga-lūkan "to shut," Old Norse lúka "to close," lykna "to bend the knees," Old High German liohhan "to pull," Old English lūcan "to plait;" Hellenic: Ancient Greek λύγος (lygos) "twigs"
luego (Adverb) "soon," "then," "later"

10th cent. From Latin loco "at the time," ablative form of locus "place." Old Latin stlocus. From Proto-Italic *steloko- 'id.' From Proto-Indo-European *stel- "to place" with an unknown suffix *-oko-.

Romance: Western Vulgar Latin: French louer, Italian locare