A bilingual person is defined as a person who speaks two languages fluently. However, for some people who define themselves as bilingual, the double dose of fluency is lost.

Aaron Eckstein, a junior at the University of Southern California and a Spanish speaker, is one of those bilingual people.

"When I was with my friends at school or in the classroom, I was always speaking English so it was really easy to practice, but Spanish kind of deteriorated and went downhill after that," said Eckstein, who grew up speaking Spanish and has family from Mexico City.

He has tried to regain his Spanish, taking AP classes in high school and minoring in the language at USC, but some aspects of his native tongue still confuse him. In Spanish, there are two words for "the": el for masculine nouns and la for feminine nouns.

Aaron Eckstein, childhood photo. (Courtesy of Aaron Eckstein)
Aaron Eckstein, childhood photo. (Courtesy of Aaron Eckstein)

"You have to think about what the next word is going to be to change that. It's a very simple kind of grammar rule, something that we would learn in like elementary school, but it's tough for me, because I have to think about it in English," Eckstein said.

Olivia Martinez, an ESL lecturer at USC's American Language Institute, said that what happened to Eckstein is very common.

"For the younger generations, they tend to generally be speaking English with their peers, and do the code switching into Spanish, because usually their English is stronger. That's the language they socialize in at school, and so that's usually what happens," she said.

Code switching, Martinez explained, is what happens when people combine two or more languages into their speaking. This can lead to the creation of linguistic hybrids, like Spanglish.

This applies to other languages besides Spanish. USC student Diana Ciocan, a native Romanian speaker who moved with her family from Romania to Canton, Ohio, when she was 10 years old, finds herself code-switching between Romanian and English at home.

Diana Ciocan, childhood photo. (Courtesy of Diana Ciocan)
Diana Ciocan, childhood photo. (Courtesy of Diana Ciocan)

"I speak Romanian with my mom at home, and with my aunt and uncle and some other family members that I have in Ohio. That's more like Spanglish, but with Romanian we haven't come up with a term for it yet," she said. "Whichever word comes to me faster is the word I say."

Ciocan knew some English before moving to Ohio, as it is taught in Romanian schools as early as second grade; but that was primarily British English, as that is the type of English primarily taught in European schools. Her family also hired a private tutor for her once they knew they would move to America.

"The accents were different than what I had learned. So it was hard for like six months," Ciocan said.

Because she was so young, she does not remember everything about the experience, but said she remembers finding English weird.

"I remember how different it was to learn certain words. Like, for example, 'hoodie' for me was a weird word for me to learn because they are literally focusing on that one piece of the of the item, like the hood and making the whole thing called the hoodie."

While some immigrant parents insist on their children speaking their native language, linguistics expert Martinez said that others insist on English.

"Oftentimes the idea is that if my child speaks our language then they will not speak English as well as they should or they will not be as successful with English, especially at school," she said.

This can lead to communication gaps between parents and children.

"The parents don't insist on the children speaking the language, and so the parents will speak in the native language, and the children will answer in English," Martinez said. "Suddenly, the less communication there is, the less language they retain, and they end up losing it."

Zsuzsa Londe, an assistant professor at USC's American Language Institute, has lived in the United States for almost 40 years, but spent the first 27 years of her life in Hungary. She knows many languages besides her native Hungarian, including German, English, French, Serbo-Croatian and Italian. She is also currently studying American Sign Language.

When Londe was 7 years old, her parents sent her to live in East Germany for a month with a family she never met before in order to improve her German. After coming home, Londe said, she could hardly speak Hungarian.

"A child's brain and mind is such like a sponge, and I was speaking so much German in Germany that when I came back I was translating from German into Hungarian," she said. "I will never forget my mom crying because she didn't understand her own daughter."

Being an imperfect bilingual speaker can cause feelings of isolation, of feeling like an outsider in what is supposed to be your community. For many, the connection between language and culture is not necessarily verbalized, but its effects are felt once you realize you cannot carry on a conversation with your grandparents or when you miss out on a joke.

For USC student Adlih Calderon, it is the little things that trip up her Spanish.

Adlih Calderon, childhood photo. (Courtesy of Adlih Calderon)
Adlih Calderon, childhood photo. (Courtesy of Adlih Calderon)

"I still have everyday trouble saying four and room in Spanish, because they're very similar, so I don't know. My parents always correct on whether it's cuatro or cuarto," she said.

She does not feel judged by her lost Spanish fluency, however. "When I use English at home they (my parents) are like 'talk to your sister in Spanish' because my sister is worse than me," Calderon said.

Being bilingual is more than just speaking two languages fluently.

"Language and culture are very closely interconnected, because a lot of the times the way that we express ourselves, the expressions we use, the idioms we use, the metaphors we use, are tightly linked to culture," Martinez said.

Adlih Calderon, contemporary photo. (Courtesy of Adlih Calderon)
Adlih Calderon, contemporary photo. (Courtesy of Adlih Calderon)

For Adlih Calderon, it is an expression of her Mexican American identity.

"So it's like I'm caught in between the cultures and that's a good thing and also a bad thing because they just see me as a Chicana, which is an American-born Mexican," she said. "So it can be difficult sometimes because like I don't speak (Spanish) 100 percent or like I speak it improperly."

For Diana Ciocan, it is the ability to perceive the world and express herself in two different ways. "Each language has a way of like — any rhetoric that you use shapes how you perceive the thing you are talking about," she said.

Diana Ciocan, contemporary photo. (Courtesy of Diana Ciocan)
Diana Ciocan, contemporary photo. (Courtesy of Diana Ciocan)

She notices this when it comes to talking about love. One of her pet peeves about the English language is that "love" is used for everything — romantic love, familial love, platonic love, etc. — while in Romanian, there are so many different words used to talk about love.

"It feels more intimate to me," she said.

Aaron Eckstein, contemporary photo. (Courtesy of Aaron Eckstein)
Aaron Eckstein, contemporary photo. (Courtesy of Aaron Eckstein)

For Aaron Eckstein, Spanish is about asserting his identity.

"You know when people kind of look at me, they…a lot of people kind of profile, and would never think that I am half-Mexican," he said. "It's just so cool to kind of say, 'Yeah, I mean I do speak Spanish, I'm half-Mexican, my family is from Mexico City.'"

Hear more stories about losing your familiary with your native language on Annenberg Media's Interactives page.

Kylie Harrington and Grace Bain contributed to this report.