half-hearted
unenthusiastic
Laodicean
bland
changeable
cold
cool
depressed
fervorless
indecisive
indifferent
infirm of purpose
infirm of will
insincere
insipid
irresolute
lukewarm
milk-and-water
milky
mushy
neuter
neutral
perfunctory
tasteless
tepid
timid
ungenerous
unkind
vapid
watery
wishy-washy
zealless
apathetic
backhanded
comradely
conspiratorial
convulsive
cursory
curt
deadspeak
deprecatory
desultory
dismissive
diversionary
dubious
faint-hearted
ham-fisted
hesitant
ineffectual
insouciant
last-ditch
maniacal
military-type
mirthless
nonchalant
reluctant
roundhouse
rueful
self-deprecating
self-deprecatory
sheepish
sideways
sidewise
spasmodic
tacit
tardy
tentative
unconvincing
undecided