Amass and build up both mean to grow a holding over time, but they emphasise different things. Amass is to gather a large quantity by deliberate effort, with the stress on the resulting size — you amass a fortune, an army, power. Build up is to increase, develop or strengthen something step by step, with the stress on the process and on getting stronger — you build up reserves, muscle, momentum. Amass is about the magnitude you end with; build up is about the developing along the way.
Both verbs add to a store, so 'amass reserves' and 'build up reserves' overlap. The emphasis differs. Amass, from the Latin massa ('a lump'), points at the bulk you finish with and the ambition behind it: a great quantity, gathered on purpose. Build up, the everyday phrasal verb, points at the gradual developing or strengthening — course by course, rep by rep, the thing grows sturdier. So a magnate amasses a fortune (the size is the point), while an athlete builds up strength (the developing is the point). Both grow a holding; one names the heap, the other the climb.
amass
To amass is to gather a great quantity on purpose — a fortune, an army, a vast collection, power. Where things accumulate almost on their own and you gather whatever is to hand, to amass is to build up a large amount through deliberate effort, with the emphasis on sheer size. It often carries a tint of ambition or greed: people amass wealth, regimes amass weapons. From the Latin massa, 'a lump', what you amass ends up a substantial, weighty whole.
build up
To build up is to increase or strengthen something step by step until it amounts to something solid — reserves, muscle, momentum, a reputation, or the tension before a release. It is the hands-on, everyday twin of accumulate: where things accumulate almost on their own, you build up by adding deliberately, one layer onto the last. The phrasal verb leans toward development and strength, and it cuts both ways — you can build up savings and stamina, or let pressure build up until something finally gives.
| amass | build up | |
|---|---|---|
| Meaning | gather a large amount by effort | increase, develop or strengthen gradually |
| Emphasis | the resulting size/bulk | the developing process and strength |
| Register | formal-ish | everyday, phrasal |
| Connotation | ambition, often greed | neutral to positive (growth, strength) |
| Often with | a fortune, wealth, power, an army | reserves, strength, momentum, a reputation |
| Noun | amassment | buildup |
Both grow a holding — pick by what you stress. Amass is the treasure hoard: someone deliberately heaps up a large amount and the size is the whole point (amass a fortune, amass power). Build up is the brick wall: you develop or strengthen something course by course, and the climb is the point (build up strength, build up reserves). If you mean a big quantity gathered on purpose, use amass; if you mean steadily developing or strengthening, use build up. Tip: you amass wealth, but you build up muscle.
amass
- iShe amassed a vast collection of first editions over thirty years.
- iiThe party amassed enough seats to govern outright.
- iiiDecades of trade let the city amass extraordinary wealth.
build up
- iHe built up his small stall into a chain of shops.
- iiThe team built up momentum with three straight wins.
- iiiIt takes months to build up the stamina for a marathon.
They overlap when a large holding develops over time — a firm can amass or build up reserves. But keep the tell: amass fixes on the large end result (and often on greed), while build up fixes on the gradual strengthening. You build up muscle or confidence (a developing), where 'amass' would sound odd; you amass a fortune (a bulk), where 'build up' sounds milder.