paed

The root paed comes from Greek pais (genitive paidos), meaning 'child,' and its close relative paideia, 'education, the raising and shaping of a child.' For the Greeks these two ideas were inseparable: to deal with a child was to educate it, and education was simply the proper rearing of the young. From this single seed English grew a small but striking family of words.

The most familiar member is encyclopedia. It comes from the Greek phrase enkyklios paideia — 'education (paideia) in the full circle' (en 'in' + kyklos 'circle'). The idea was the complete, all-round learning a free citizen should have, covering the whole circle of subjects rather than one narrow corner. English squeezed the phrase into a single word, and it came to name a book that holds the entire circle of knowledge. (Note the cycl- inside: it belongs to the 'circle' root, not to paed.)

The teaching words show pais joined to another Greek root, agōgos 'leader' (from agein 'to lead'). A paidagōgos was originally the household slave who 'led the child' to school. From him we get pedagogy, 'the art of leading children' — i.e. teaching; pedagogue, the teacher himself (now often with a stiff, fault-finding tone); and the adjective pedagogic. The same scolding, rule-obsessed flavor shows up in pedant, a person who fusses over the petty details of learning and loves to show it off.

Two cautions. First, spelling: British English keeps the Greek ae (paediatric, encyclopaedia, paedophile), while American English drops it to e (pediatric, encyclopedia). Same root, two dresses. Second, and more important: this ped 'child' looks exactly like the Latin ped 'foot' (as in pedal, pedestrian, pedestal), but they are completely unrelated — same shape, different ancestry. A pedicure treats your feet (Latin ped); a pediatrician treats your children (Greek paid). When you see ped, ask whether the topic is feet or children, and you will rarely go wrong.

The child-as-patient sense also gives us the medical words: pediatrics, the branch of medicine caring for children, and orthopedic — literally 'straightening children,' since the field began with correcting the bent posture and bones of growing children (orthos 'straight' + paideia). So the whole family circles back to the same image: the child, and what we do to raise, teach, and mend it.