blow up
phrasal verb.to explode or to destroy something with an explosion; it can also mean to fill something with air, like a balloon.
phrasal verb.to undergo or cause to undergo a sudden, violent expansion or destruction; also used transitively to denote the inflation of an object.
“The soldiers had to blow up the old bridge.”
“We need to blow up fifty balloons before the birthday party starts at noon.”
“The structural integrity of the building was so compromised that the demolition crew decided to blow up the entire north wing.”
when it means to inflate, it is usually transitive; when it means to explode, it can be transitive or intransitive.
mention the informal figurative sense 'to get very angry' (e.g., 'he blew up at me') to show how the idea of an explosion applies to emotions.
if using a pronoun as the object, it must go between the verb and the particle.
From Middle English blow up, blowe up, dissimilated forms of earlier Middle English upblowen (> English upblow), equivalent to blow + up. Compare West Frisian opblaze (“to blow up, inflate”), Dutch opblazen (“to blow up, inflate”), German aufblähen and aufblasen (“to blow up, inflate”), Swedish blåsa upp (“to blow up, inflate”), Icelandic blása upp (“to blow up, inflate”), Gothic 𐌿𐍆𐌱𐌻𐌴𐍃𐌰𐌽 (ufblēsan, “to blow or puff up”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.