Structure
What are the elements that make up this word's structure?
In my work with younger students, we sometimes play a game called Suffix or Not? in order to help them begin identifying these elements that occur after a base in a word. Several students might say the water is a suffix or the string is a suffix.
The easiest way to determine if something is a suffix or not is to remove the suffix and see if what you have left is a word. This works well on words like playing or camper. However, what about our suffixes above? Well, that usually requires going through the Four Question Framework like we are doing now to see how the word is built.
Harb + ing + er?
I've never been harbing or had a harb, but that doesn't mean that couldn't be the base of our word. After all, I've never been rupting or had a vade, but interrupting and invader are both words. Perhaps bound base, like
Let's take a look at the entry in Etymonline.
When it entered our lexicon in the late 15th century, English speakers spelled this word herbengar. Then, a harbinger was "a person sent ahead to arrange lodging." Let's trace the word back in time by following the "froms" in the entry.
Middle English herberger
OF herbergeor
OF herbergier
OF herber
Frankish *heriberga
Germanic *harja-bergaz
First let's note the asterisk in those two entries. The asterisk is a linguistic symbol that means these words are unattested in written form. They are often recreated through methods linguists use to piece together how an earlier form may have been pronounced. Since they are unattested, we will not refer to them to determine the orthographic journey of our word.
We can note that these words we got from French did not come from Latin, although French is a daughter language of Latin. The Franks were a Germanic people who invaded the Roman Empire in the 5th century. We see the Frankish term coming from a Germanic compound. Although modern German descends from one branch of the Germanic language family, this language family also includes Dutch, Swedish, Afrikaans, and English. The Germanic people were a group of tribes that lived in Northern Europe that may have actually shared little identity other than that they spoke what are now considered Germanic languages.
The biggest thing to notice in its orthographic journey is the insertion of the grapheme passenger or messenger. Certainly, if we are following the typical pattern of adding the agent suffix <-er>, we would have *messager or *passager.
The grapheme
The intrusive herbergier is an "agent noun." The suffix <-er> is an agent noun suffix in English, forming people (teacher) or things (expander) that "do" the verb that is the stem or base. We see that same French agent noun suffix <-ier> in the English cashier.
I would offer that it's not terribly productive to analyze this far. After all, here's what we are left with:
harbing + er
In the Oxford English Dictionary, I do see an entry harbinge, which is the verb form of this word.
harbinge/ + er
That single final non-syllabic
The Oxford says this word is obsolete. The last use is listed in the 1800s. Although it provides interesting discussion, I would probably leave this word intact for a student rather than analyze it into a word sum.