insipid (adj.)
- arid
- banal
- bare
- barren
- bland
- blank
- bleached
- bloodless
- bromidic
- changeable
- characterless
- clear
- cold
- colorless
- common
- commonplace
- dead
- devoid
- dilute
- diluted
- dismal
- distasteful
- dreary
- dry
- dull
- dusty
- effete
- elephantine
- empty
- etiolated
- fair
- fairish
- featureless
- feeble
- flat
- flavorless
- halfhearted
- heavy
- ho-hum
- hollow
- humdrum
- inane
- indecisive
- indifferent
- innocuous
- irresolute
- jejune
- lackluster
- leaden
- lifeless
- low-spirited
- matter-of-fact
- mediocre
- medium
- middling
- mild
- milky
- moderate
- modest
- mundane
- mushy
- namby-pamby
- neutral
- null
- ordinary
- pale
- pallid
- passable
- pedestrian
- plain
- plodding
- pointless
- poky
- ponderous
- prosaic
- prosy
- pulpy
- respectable
- sapless
- savorless
- slight
- slow
- so-so
- soft
- solemn
- spiritless
- stale
- sterile
- stiff
- stodgy
- stuffy
- subdued
- superficial
- tame
- tasteless
- tedious
- tenuous
- thin
- tiresome
- tolerable
- unappetizing
- unembellished
- unflavored
- unimaginative
- unimpassioned
- uninteresting
- unrelieved
- unromantic
- unsavory
- vacant
- vacuous
- vapid
- void
- washy
- watered
- watery
- weak
- wearisome
- white
- wishy-washy
- wooden