laŭvole

Three pieces, read straight off. Laŭ is the preposition according to. Vol- is the root of voli, to want, and volo is the will. -E is the adverb ending. So laŭvole is according to the will, which is to say at will, as you like, freely. And laŭvola with the adjective ending is the word you will actually use more often: optional. Laŭvola kurso is an optional course; laŭvola donaco a voluntary contribution.

The laŭ- family is now complete, and it is worth seeing it in one place.Laŭ is unusual among Esperanto prepositions in how freely it compounds, and the course has now taught all five:

• laŭdire (1907) - according to what is said: reportedly, allegedly.
• laŭvorta (2399) - according to the words: literal, word for word.
• laŭleĝa (2452) - according to the law: lawful.
• laŭvice (2517) - according to the queue: in turn, one after another.
• laŭvole (2598) - according to the will: at will.

Once you have seen five, the sixth is free. Laŭplaĉe is as one pleases, laŭeble as far as possible, laŭbezone as needed, laŭmezure made to measure. None of them has to be learned separately; the pattern is according to X, and you supply the X.

Two decoys with the same first three letters.Laŭta at rank 482 means loud, and laŭdi at 1306 means to praise. Neither is a laŭ- compound. Laŭt- is one root, from German laut; laŭd- is one root, from Latin laudare. If you cut them at the laŭ you are left with -ta and -di, which mean nothing, and that is the test - as always, the seam is real only when both halves are words.

How it behaves in a sentence. Laŭvole is an adverb and sits where adverbs sit, usually after the verb it modifies: agu laŭvole, venu laŭvole. Do not confuse it with libervole, which is voluntarily in the sense of not under compulsion - a prisoner does not leave libervole, whereas a guest leaves laŭvole. And nevole, unwillingly, is its opposite number.