late 14c., "book of permanent tables of astronomical data," attested in Anglo-Latin from mid-13c., via Old French almanach or directly from Medieval Latin almanachus, a word of uncertain origin and the subject of much speculation. The Latin word is often said to be ultimately from Arabic somehow, but an exact phonological and semantic fit is wanting: OED connects it to a supposed Spanish-Arabic al-manakh "calendar, almanac," which is possibly ultimately from Late Greek almenichiakon "calendar," which itself is said to be of Coptic origin. But the author of English words of Arabic Ancestry makes a detailed case "that the word almanac was pseudo-Arabic and was generated within the circle of astronomers in Paris in the mid 13th century."
Those are all interesting suggestions, but one not mentioned in that entry allows for a connection to a Hebrew word. Stahl mentions a theory that does in his Bilingual Etymological Dictionary of Spoken Israeli Arabic and Hebrew, and it also appears in other sources, such as this and this. He points out that in Arabic manakh means "weather, climate" and derives from a word meaning "where the camels kneel and rest." That place was a camp, and for nomadic tribes, it took on the sense of a permanent settlement. This sense of permanence, became associated with other constant or expected things - in this case, the weather. And so an almanac was a book which included certain astronomical predictions (like the times of sunrise and sunset), dates for holidays, and meteorological forecasts.
This Arabic root - either via nakha, "kneel" or manakh, "camp" - is cognate with the Hebrew word root נוח meaning "to rest." That root gives us the word menucha מנוחה. In Modern Hebrew menucha means the condition of "rest, respite" or "calm, serenity." But in the Bible, it generally (perhaps always) means a resting place. In many verses it is synonymous with nachala נחלה - "inheritance", as in Devarim 12:9 where both refer to the Land of Israel:
כִּי לֹא־בָּאתֶם עַד־עָתָּה אֶל־הַמְּנוּחָה וְאֶל־הַנַּחֲלָה אֲשֶׁר־ה' אֱלֹהֶיךָ נֹתֵן לָךְNow you have not yet come to the resting place [menukha] and hereditary land that God your Lord is giving you.
Another verse with the same meaning is Bereshit 49:15, which compares menucha to aretz (land):
...וַיַּרְא מְנֻחָה כִּי טוֹב וְאֶת־הָאָרֶץ כִּי נָעֵמָהBut he sees that the resting place [menucha] is good, and that the land is pleasant...
In this way, menucha is similar to the word meluna מלונה - "lodge" (and related to the word malon מלון - "inn"), which derives from the root לון - "to lodge, to pass the night." Meluna is clearly a place, and so too menucha means a resting place.
Of course, it's easy to conflate a resting place and a state of rest, and so there are some verses where it's not clear which meaning is intended. In the end, just as the Arabian nomads appreciated the chance to let their camels kneel and rest, so to did the nomadic tribes of Israel appreciate the chance to stop wandering and settle in their homeland. The resting place caused a state of rest.