from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
INFRA, Latin. Below, under, beneath, underneath. The opposite of supra,
above. Thus we say primo gradu est supra, pater, mater; infra, filius,
filia. In the first degree of kindred in the ascending line; above, is the
father and the mother; below, in the descending line, the son and daughter.
Inst. 3, 6, l.
2. In another, sense, this word signifies within; as, infra corpus
comitatus, within the body of the county; infra proesidia, within the
guards.
3. It also signifies during; as infra furorem during the madness.