Other forms: sustained, sustaining, sustains
To sustain something is to keep it going over time. Savings that sustain a family for a year, a fire you sustain by feeding it wood, a note the singer sustains until the room goes still.
The second meaning is the one that catches learners out: to sustain an injury, a loss or damage means to suffer it. 'Two passengers sustained minor injuries' is newsreader English for two people were slightly hurt, and nobody talks that way outside a report. In court, 'objection sustained' means the judge agrees and the question is dropped. As an adjective, sustained means kept up without a break — sustained applause, a sustained effort, sustained pressure on the defence. The family runs on into sustainable and sustainability, which are about keeping something going without using it all up.
1verbmaintainTo keep something going over a period of time.
“The charity could not sustain three offices on that income.”
2verbgiveTo give someone or something the strength or support to continue.
“Bread and sweet tea sustained them until the evening.”
3verbsustainIn formal and news English, to suffer an injury, loss or damage.
“The driver sustained a broken wrist in the crash.”
formal in this meaning — an editor’s judgement
4verblawIn law, to uphold an objection or claim as valid.
“The judge sustained the objection and the lawyer sat down.”
The Latin parts are from below and to hold. To sustain something is to hold it up from underneath, so it never falls.
hooks ontohold
Sustain came through Old French sustenir from Latin sustineō, 'to uphold'. Take the Latin apart and it is sub-, 'from below, up', with teneō, 'to hold' — holding a thing up from underneath. Every modern use still fits that picture, even sustaining an injury: you are the one bearing the weight.
Proto-Indo-European
*ten-
Latin
sustineō — to uphold
Old French
sustenir
Middle English
susteinen
English, today
sustain
Built from
From Middle English susteinen, sustenen, from Old French sustenir (French soutenir), from Latin sustineō (“to uphold”), from sub- (“from below, up”) + teneō (“hold”).
Etymology from Wiktionary, CC BY-SA