A popular rallying cry of radio spindoctors and nativist pundits alike is that this is America, and people should just "speak English." OK, but here's the thing: there are actually a lot of languages you're speaking when you speak English. Because that's how language works. It changes over time, picks up words from different languages, and is usually a crazy amalgamation of history.
When it comes to English, because its influences are so disparate, it is difficult to determine exactly what languages influenced English the most. Even most native speakers have little awareness of the languages they're speaking when they speak English. Through conquest, assimilation, and immigration, English has evolved over many centuries into a pastiche of vocabulary representing many different cultures. From the earliest Viking invasion to the most recent wave of immigration, the English language has continued to evolve, reflecting the languages that you have no idea you are speaking when you speak English.
One of the ethnic groups to successfully invade England were the Vikings, and, by virture of their superior conquering abilities, they contributed a great deal of vocabulary to the language we now call English. Beginning in the 8th century CE, these marauders, coming mostly from what is now known as Denmark, successfully colonized a lengthy part of present-day eastern England. They created a broad swath of conquered land that was called the Danelaw.
This settlement would only last until the middle of the 10th century, but that was plenty of time for the Vikings to contribute words to the English language. These include the word "berserk" (from the Viking "bersekr," or "bear shirt," the garment frenzied Vikings would wear as armor in battle), "club" (from "klubba," obvious, especially when you were hit over the head), "ransack" ("rannsaka," to "search a house"), and "slaughter" ("slatra," "to butcher").
Notably, Vikings also contributed the names of the days of the week, which are named after Norse gods. Thursday, for example, came from the word "Þorsdagr" or "Thunresdæg," which mean "Thor's Day." Wednesday and Friday are named for Odin and Freya, respectively.
Gaelic is frequently associated with the Irish. However, Gaelic is derived from a people known as the Gaels, a Celtic tribe who relocated from the European mainland and settled in both Ireland and Scotland. While words in both Scottish Gaelic and Irish Gaelic are similar, the pronunciation is very different and would not be understood by the respective speakers of each language. A few English words that originated from Scottish Gaelic are "clan," "shindig," "slogan," and "smashing." Some English words that originated from Irish Gaelic are "hooligan," "whiskey," "banshee," and "brogue."
Spanish has entered English in various ways with different ethnic origins. Traditional Castillian Spanish originated with the Spanish colonization of the Americas that occurred in the 15th and 16th centuries. Such words as albino, cargo, cigar, embargo, guitar, mesa, rodeo, canyon, and salsa all share a Spanish origin. Other words were adopted during the Southwestern expansion of the United States in the late 19th century. Chocolate, taco, and tortilla are among the many English words that emanated from indigenous Mexican origins. Spanish also contributed words that initially were derived from Arabic sources during the Moorish occupation of the Iberian Peninsula. These include the words algebra, alchemy, and algorithm.see more on Spanish Language
In 1066, William the Conqueror, the Duke of Normandy, defeated and killed King Harold at the battle of Hastings, subsequently crowning himself King of England. Because the Normans were descended from Vikings, AKA "Norseman," and also from various parts of present-day France, they spoke various languages with different origins. These languages eventually blended into what was known as Anglo-Norman French. Because England was being ruled by a Norman, and most nobleman were connected to the Norman king, this language became the official language in the government, schools, and universities. It was the language of breeding, education, and propriety.
Because of the official nature of the Norman French influence, many words related to government and law came from this Norman French. These words included sovereign, majesty, revenue, mayor, viscount, as well as prince, princess, baron, and even the word nobility itself. Religious words with a Norman-French origin include baptism, prelate, cardinal, virgin, saint, reverend, adore, and sacrifice. The number of words adopted into English as a result of the Norman Invasion are actually too numerous to list.