  It is speculated that some weakly active comets may be transitional objects
between active and dormant comets. These objects are at a unique stage of the
evolution of cometary nuclei, as they are still identifiable as active comets,
in contrast to inactive comets that are observationally indistinguishable from
low albedo asteroids. In this paper, we present a synthesis of comet and meteor
observations of Jupiter-family comet 209P/LINEAR, one of the most weakly active
comets recorded to-date. Images taken by the Xingming 0.35-m telescope and the
Gemini Flamingo-2 camera are modeled by a Monte Carlo dust model, which yields
a low dust ejection speed ($1/10$ of that of moderately active comets),
dominance of large dust grains, and a low dust production of $0.4~\mathrm{kg
\cdot s^{-1}}$ at 19~d after the 2014 perihelion passage. We also find a
reddish nucleus of 209P/LINEAR that is similar to D-type asteroids and most
Trojan asteroids. Meteor observations with the Canadian Meteor Orbit Radar
(CMOR), coupled with meteoroid stream modeling, suggest a low dust production
of the parent over the past few hundred orbits, although there are hints of a
some temporary increase in activity in the 18th century. Dynamical simulations
indicate 209P/LINEAR may have resided in a stable near-Earth orbit for $\sim
10^4$~yr, which is significantly longer than typical JFCs. All these lines of
evidence imply that 209P/LINEAR as an aging comet quietly exhausting its
remaining near surface volatiles. We also compare 209P/LINEAR to other low
activity comets, where evidence for a diversity of the origin of low activity
is seen.
