maintain

v. keep in existence, sustain; keep in good condition, preserve; support, provide for; affirm, declare, assert

Maintenance management or Maintenance, ('MRO), is fixing any sort of mechanical or electrical device should it become out of order or broken (repair) as well as performing the routine actions which keep the device in working order (maintenance) or prevent trouble from arising (preventive maintenance).
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(v. t.)
To keep possession of; to hold and defend; not to surrender or relinquish.
  

(v. t.)
To hold or keep in any particular state or condition; to support; to sustain; to uphold; to keep up; not to suffer to fail or decline; as, to maintain a certain degree of heat in a furnace; to maintain a fence or a railroad; to maintain the digestive process or powers of the stomach; to maintain the fertility of soil; to maintain present reputation.
  

(v. t.)
To continue; not to suffer to cease or fail.
  

(v. t.)
To bear the expense of; to support; to keep up; to supply with what is needed.
  

(v. t.)
To affirm; to support or defend by argument.
  

1) Concerning altitude flight level, the term means to remain at the altitude flight level specified. The phrase "climb and" or "descend and" normally precedes "maintain" and the altitude assignment; e.g., "descend and maintain 5,000". 2) Concerning other Air Traffic Control (ATC) instructions, the term is used in its literal sense; (e.g., maintain Visual Flight Rule (VFR)). (FAA4)

Verb
1. keep in a certain state, position, or activity; e.g., "keep clean"; "hold in place"; "She always held herself as a lady"; "The students keep me on my toes"
(synonym) keep, hold
(hyponym) pressurize, pressurise
(derivation) upholder, maintainer, sustainer
2. keep in safety and protect from harm, decay, loss, or destruction; "We preserve these archeological findings"; "The old lady could not keep up the building"; "children must be taught to conserve our national heritage"; "The museum curator conserved the ancient manuscripts"
(synonym) conserve, preserve, keep up
(hypernym) keep
(hyponym) embalm
(derivation) care, maintenance, upkeep
3. supply with necessities and support; "She alone sustained her family"; "The money will sustain our good cause"; "There's little to earn and many to keep"
(synonym) sustain, keep
(hypernym) have, have got, hold
(hyponym) patronage
(derivation) maintenance
4. state categorically
(synonym) assert, asseverate
(hypernym) insist, take a firm stand
(hyponym) allege, aver, say
5. of power or authority
(synonym) wield, exert
(hypernym) have, have got, hold
6. maintain for use and service; "I keep a car in the countryside"; "She keeps an apartment in Paris for her shopping trips"
(synonym) keep
(hypernym) have, have got, hold
7. maintain by writing regular records; "keep a diary"; "maintain a record"; "keep notes"
(synonym) keep
(hypernym) record, enter, put down
8. state or assert; "He maintained his innocence"
(synonym) defend
(hypernym) affirm
(hyponym) vindicate
9. support against an opponent; "The appellate court upheld the verdict"
(synonym) uphold
(hypernym) confirm, reassert
(hyponym) justify, vindicate
10. observe correctly or closely; "The pianist kept time with the metronome"; "keep count"; "I cannot keep track of all my employees"
(synonym) observe, keep