  We search for gravitational-wave signals produced by cosmic strings in the
Advanced LIGO and Virgo full O3 data set. Search results are presented for
gravitational waves produced by cosmic string loop features such as cusps,
kinks and, for the first time, kink-kink collisions.cA template-based search
for short-duration transient signals does not yield a detection. We also use
the stochastic gravitational-wave background energy density upper limits
derived from the O3 data to constrain the cosmic string tension, $G\mu$, as a
function of the number of kinks, or the number of cusps, for two cosmic string
loop distribution models.cAdditionally, we develop and test a third model which
interpolates between these two models. Our results improve upon the previous
LIGO-Virgo constraints on $G\mu$ by one to two orders of magnitude depending on
the model which is tested. In particular, for one loop distribution model, we
set the most competitive constraints to date, $G\mu\lesssim 4\times 10^{-15}$.

General Relativity and Quantum Cosmology;Cosmology and Nongalactic Astrophysics;High Energy Physics - Theory