Pronunciation: [we͡əɹˈɪntə͡ʊ] (IPA) 
The word "whereinto" is spelled as /wɛrˈɪntuː/, which is pronounced as "wair-IN-too." It is a combination of two words, "where" and "into." This word is used to refer to a place or thing into which something is placed or inserted. "Whereinto" is considered an archaic word and is not commonly used in modern English. However, it can still be found in old literature, poetry, and certain legal documents.
Whereinto is an archaic adverb that is primarily used in formal or old-fashioned writing. It is derived from the combination of two words: "where" and "into." The term is used to indicate the destination or direction that someone or something is going into or entering.
The adverb "whereinto" is typically employed when referring to a place or position that is being entered or penetrated. It denotes the specific location or target that is being directed toward or entered into. For example, one might say, "She stepped into the mysterious cave, whereinto darkness enveloped her."
In essence, "whereinto" serves as a more precise alternative to the word "into." It emphasizes the notion of entering or going into a specific location or situation rather than simply indicating movement or direction.
The usage of "whereinto" has become less common in contemporary English, primarily due to its archaic nature. However, it is still occasionally encountered in formal or academic contexts, particularly in literature, historical texts, or legal documents where a more formal or antique language style is employed.
In conclusion, "whereinto" is an adverb that signifies the entry or movement into a specific location or position. Though antiquated, it can still be found in certain types of writing where a more formal or old-fashioned vocabulary is appropriate.
Into which.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
The word "whereinto" can be traced back to Middle English, with its earliest recorded usage dating to the 1300s. It is a compound word formed by combining the adverb "where" and the preposition "into".
"Where" has Old English roots and can be traced back to the Proto-Germanic word *hwær, meaning "at or to what place". It eventually evolved into the Middle English word "wher", which is similar in form and meaning to the modern "where".
The preposition "into" also has Old English origins and can be traced back to the Proto-Germanic *in, meaning "in, into". It gradually developed into the Middle English word "into", which shares the same meaning as the modern word.
The combination of "where" and "into" resulted in the word "whereinto", which is used to express movement or direction into a particular place or thing.
