The only free and comprehensive online etymological dictionary of the Spanish language
entender (Verb) "to understand"
From Latin intendere "to focus on." From in- and tendere "to reach for" (see en- and tender respectively).
Indo-European
Romance
Asturian entender, Portuguese entender, Catalan entendre, French entendre, Italian intendere, Aromanian ntindu, Romanian întinde, Sardinian intèndhere