to keep (a building, machine, etc) in its required state of repair or operation
to allow or enable (something) to continue
to continue or keep up (a posture, appearance, etc)
to support, sustain, or provide for (e.g. dependants)
to affirm or assert (something) in argument
maintainable adj
maintainer noun
[Middle English mainteinen via Old French and late Latin from Latin manu tenēre to hold in the hand]