long cylindrical things such as glasses of drink, pairs of jeans, pens or trains and buses / films or TV shows / home runs or goals / rounds of a match in boxing, wrestling or judo

current, this, the matter in question / original, actual, base

book / this / main / real / actual / true

one, 1 / the first in order, foremost / the beginning / the best / a kind of; one of something / (card games) an ace / unity / the bottom string of a shamisen or other Japanese musical instrument

(calculus) constant of integration - a constant term added to a particular antiderivative to make it represent its whole family of antiderivatives

(physics, chemistry) Avogadro's number, Avogadro constant (number of atoms present in 0.012 kilograms of isotopically pure Carbon-12)

(physics) the Planck's constant

(algebra) constant term

everything

(colloquial) current boyfriend