funto

One root, no seams, and a fence you will thank yourself for. Funto is a single borrowed root plus the noun ending. There is nothing inside it. But look at the shape of it, because the neighbourhood is crowded:

• funto - a pound.
• fundo, rank 773 - a bottom, the depths. One letter apart, and the letter is voiced against unvoiced: funto has the t of tea, fundo the d of deed. La fundo de la maro is the sea bed. La funto de la maro is nothing at all.
• fondo - a founding, from fondi, to found.
• fonto - a spring or a source.

Four words, one vowel and one consonant between them, and Esperanto's completely regular spelling means each is pronounced exactly as written. That is the saving grace: unlike English, there is no ambiguity once you have heard it correctly. The work is at the listening end, not the reading end.

Two senses, and both are current.

The weight. Historically the pound of the old continental systems, which varied by city and settled around 500 grams in the German-speaking world; today the imperial and US pound of 453.6 grams, which is what an Esperanto text about Britain or America will mean. The metric world uses kilogramo at rank 1,830 and its clipped everyday form kilo at 2,396, and those are what you should write for anything modern. Funto is for old recipes, historical prose and translations out of English.

The currency. La brita funto, the pound sterling - funto sterlinga when somebody is being formal. Also the Egyptian, Syrian and Lebanese pound, all of which are funtoj in Esperanto, and the old Irish one. The euro is eŭro and the dollar is dolaro; the pattern is that currency names come over unaltered with -o on the end, so you can generally guess them.

A usage note on da. Funto da viando is a pound of meat, with da rather than de, because funto here is a quantity and da is the preposition for what a quantity is a quantity of. La funto de la butiko with de would be the shop's pound - the weight it uses - which is a different sentence entirely. Measures take da. This is one of the small grammatical points Esperanto is strict about and English does not mark at all.