A busy international airport.
A bustling airport.
Bustling is synonym of busy.
exists s1 s2 x1.(a_topic(x1) & n_airport(x1) & a_international(s2) & Theme(s2,x1) & a_busy(s1) & Theme(s1,x1))
exists s1 x1.(a_topic(x1) & n_airport(x1) & a_bustling(s1) & Theme(s1,x1))