French is just the greatest; who doesn't like French? And the Anglophone can step easily into French, because our English vocabulary has been enriched (that's right: enriched) with thousands and thousands of French words since 1066, when Francophone Vikings conquered England.
Anyway, by recognizing some patterns in French, it's easy to know what the English sibling or cousin of a French word is likely to be. Of course any Anglophone can recognize train, couleur, honneur, fleur, raison, raisin, appetit, detour, porter, direct, and example. In these cases the English siblings are identical, or virtually so, and we don't need to know any patterns.
But here's a pattern in French that isn't so obvious: maître, fête, côte, bête, forêt.
The pattern is the little hat on the vowels; it's a circumflex; or le petit chapeau, the...little...hat. Often, but not always, the circumflex indicates the loss of the letter s from a word, per the examples above. If we add the s back we create (or at least approximate) the English cognates: master, feast, coast, beast, forest.
The circumflex indicates the lost s so often that it always pays to try the s in a circumflexed word just to see if it helps with the meaning. For example prêtre gives us prester, which is an older version of priest in English, as in Prester John. A favorite of mine is huître. Huister...is that English? Yes, but we spell it oyster.
Don't worry if the s trick doesn't always work. For example, in rôle and diplôme it's a comment on the vowel sound. And I think sometimes the French use a circumflex just because they like how it looks.
Now you ask, if we got those words from the French, why do we say them with an s when they don't? Well, because the French still said them with an s in 1066. But the French language in England stopped changing, unlike the French in France, which kept getting more French. As Chaucer said of the Prioress around 1370:
And French she spoke full fair and fetisly
After the school of Stratford at-te Bow-e,
For French of Paris was to her unknow-e.
So the English kept the s (but sometimes in a French way: aisle, isle) as the French were letting it go. But if the French increasingly dropped the s in speech, the s didn't erase itself from French books. And I expect that Frenchmen who could write were not fond of spelling forest without its s even if nobody made the sound anymore. Does that seem unduly fussy? It's not- do you want to spell knight as it sounds? Me neither. So the French compromised: drop the s, but add the chapeau where it used to be.
But the circumflex doesn't indicate every case that an s has been dropped; see if you can figure these out: écorcher, école, étude, écrire, étonne. In these examples, adding the s gives us scorch, school, study, scribe, stun. The accent mark takes priority over the circumflex, which is implied though it's not there. So another lost-s pattern is French words which begin with an e followed by a consonant.
There's something else these lost-s-words have in common: they all are part of French's Latin patrimony. That is, école comes from schola; fête from festa; and maître from magister. And this next example is less obvious, but still solvable: château from castellum (fort, castle). But a caution is in order: not every lost-s-word comes from Latin. For example, étiquette lost its s, but its origin is Germanic.
But sticking with the likelihood that a French lost-s-word is Roman in origin, consider how many words that makes available to you, the discerning pattern sleuth, in all the Latin-sourced tongues, the Romance languages. Remember, Latin originally was simply the language of Latium, the area of central Italy inhabited by the Latini tribe. As the Latin city-state of Rome extended its empire, so spread the Latin language. But the people in Hispania, for example, already spoke their own languages. So when Latin was imposed on them, they didn't speak it as Romans did, but altered it through their existing sensibilities of pronunciation and rhythm. As the Empire later receded, Latin persisted; but only as a local language. The Latin of Hispania wasn't the Latin of Gaul or Dacia, and these local versions would eventually be recognized by their speakers as languages separate from, other than, Latin. Of course Latin herself was also the child of older tongues, but in this post Latin is the only source we'll look at.
Consider the Latin word schola. In French it's école; in Italian, scuola; in Spanish, escuela; in Romanian, şcoală (shkoala). Each version of schola reveals a pattern of each language's rhythm and sound habits; and those patterns can apply to other words. Since this post is about French, let's try étudiant. It starts with an accented e followed by a consonant; assume it's a lost-s-word with an implied circumflex. So we add the s back to get éstudiant. Allowing for our English vowel preferences, we drop the e to get student. Judging from scuola, Italian doesn't add an e in the first place, but it does want to end with a vowel for reasons of rhythm: studiante, maybe? Close, it's studente. Spanish escuela suggests we keep the French e and add a vowel at the end for rhythm...estudiante? Yes, indeed. And while in Romanian the word is student, it's worth remembering from şcoală Romanian's tendency to turn an initial s into sh, as we do with strike and stranger. Thus when English says scholar, Romanian says şcolar (shkolar).
Now this circumflex pattern is a small one; but it gives the English-speaker easy access through French to dozens of Romance words, and allows a student to jumpstart his foreign language vocabulary with just a bit of practice.