nirtzah

The Haggadah opens up with a song, to help the participants remember, via rhyme, the various actions they need to perform throughout the seder. The last section, however, is not an instruction per se - but more of a description of this final stage. This is the Nirtza נרצה section, which is followed by various songs after the seder is completed.

What does nirtza mean? I've seen it translated as "(all is) accepted" or "acceptance." The source appears to be this verse in Kohelet, which in a number of older haggadot opens the Nirtza section:

כִּי כְבָר רָצָה הָאֱלֹהִים אֶת־מַעֲשֶׂיךָ׃...
...  for your action was long ago approved by God. (Kohelet 9:7)

And so Nirtza is a time where after all of the Pesach service is completed, we can enjoy the fact that God approved our actions.

This understanding reflects the fact that in Biblical Hebrew, the verb ratzah רצה meant "to be pleased with, to be favorable to."  That is the most common meaning. There are also verses where it means "to like" or "to appease." Similarly, the derivative noun ratzon רצון means "goodwill, favor."

However, Fox, in his JPS Commentary on Kohelet writes that this is not the best translation for that verse. He says the phrase should be instead translated as "for your action was long ago desired by God." This sense of ratzah is the one commonly used today - "to want." This sense is very common in Rabbinic Hebrew, but is rarely found in Biblical Hebrew. If Fox is correct, this is probably due to Kohelet frequently using Hebrew that reflects later usage. 

Despite ratzah meaning "to want" being one of the first words learned in Hebrew (either by young children or new speakers), strangely neither Ben Yehuda nor Klein mention it in their dictionaries, rather providing only the biblical meanings.

Ratzon also changed meanings. While as we said, in Biblical Hebrew it meant "favor", in later Rabbinic writings it came to mean "will" (this is also likely the meaning in later books of the Bible, such as Esther 9:5)  In the Medieval period, much ink was spilled by rabbis who debated the nature of God's will. The rationalists, like Maimonides, much preferred to speak of God's will than His favor.

Inspired by ratzon meaning "will" (as in persistence), Eliezer Ben Yehuda took the Arabic word razin ("grave, serious") and coined the word retzini - רציני - "serious."

The sense of ratzah meaning "to be pleased" still has footing in Modern Hebrew. The related word merutzeh מרוצה means "satisfied." 

The Hebrew words for "lecture" - הרצאה hartza'ah and "lecturer" - מרצה martzeh also share the root רצה, and are related to the words we discussed above. Klein says that secondary meaning of the root meant originally "to count, enumerate, pay off" and later "to recount, narrate, deliver a lecture." He provides this etymology:

For the sense development of הִרְצָה cp. סָפַר (= he counted), סִפֵּר (= he recounted, told, narrated); Arab. manā, manā(y) (= he counted), mānā(y) (= he paid); Gk. arithmein (= to count; to pay); Eng. to tell, which means both ‘to count’ and ‘to recount’, Eng. re-count and recount; Fren. compter (= to count), and conter (= to tell, recount, narrate), which both derive from L. computāre (= to count), and It. contare, Sp. contar, which are of the same origin, and mean both ‘to count’, and ‘to tell, relate’. JAram. אַרֽצִי (= he counted, enumerated). According to several lexicographers רצה ᴵᴵ properly represents a special sense development of רצה ᴵ and orig. meant ‘to satisfy the creditor’. 

 So now perhaps this can give us another feeling when we arrive at Nirtza. We've counted (so many plagues!) and recounted the story of the Exodus. The "creditor" is indeed satisfied!