As a noun, a condition is the state something is in, or a requirement that must be met for something else to happen. As a verb, to condition means to train or prepare someone or something to behave in a certain way.
From Latin 'condiciō', meaning 'agreement, situation, stipulation', from 'condicere' ('to speak together, agree'). It entered English via Old French with both the sense of circumstances and rules.
A 'condition' can be a rule ('on one condition...') or a state ('in good condition'), but the hidden link is that both describe the setup that shapes what can happen next. In psychology, 'conditioning' shows how repeated experiences can quietly shape our reactions.
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