a bending of the knee either so it touches the floor or moves as if to do so
a bodily gesture of respect that reflects (shows) our genuine (real) belief in the Real Presence of Jesus in the Most Blessed Sacrament
a sign of adoration while the bow is a sign of reverence
a sort of deep curtsey where the right knee touches the ground
The bending of the right knee when reverencing the altar and at other times of solemn reverence. Episcopalians sometimes bow instead of genuflecting.
Genuflection is an act of reverence consisting of falling onto (usually) one knee. Today the term is used mostly in the Latin rite of the Roman Catholic Church and in churches of the Anglican Communion. The faithful who pass before the presence of the Blessed Sacrament (generally reserved in the tabernacle) are expected to genuflect on the right knee as a sign of devotion.