In our Mishna on Amud Aleph, a bachelor is referred to as a Ravak, with its Hebrew root being רק, meaning empty. As I've emphasized numerous times in the Psychology of the Daf, Hebrew is a language rich in meaning, and delving into the roots of words provides extraordinary anthropological and psychological insights.

According to the Wikipedia entry, the English word "bachelor" has an unknown origin, with its first attestation in the 12th century, where it referred to a young knight. The word in English carries connotations of a young person who is not yet fully initiated, both professionally and personally, into adulthood, often through marriage. (It's worth noting that some secular dictionaries, when encountering words with a apparent Hebrew origin, tend to stop at Greek and other ancient languages without considering Hebrew at all. Since the word "bachelor" lacks a known origin, the phonetic similarity to "Bochur," meaning a young student in Hebrew, leads to the fairly obvious conclusion that it has Hebrew roots.)

The Greek word for bachelor is ἄγαμος, "Agamos." It's a compound word with the prefix "A" meaning "not" and the suffix "Gamos" meaning "marriage," indicating one who is not married.

However, Hebrew uses a term that implies emptiness. A man who is not married is described as empty. What is this emptiness about? Koheles Rabbah (9:9) conveys: Anyone who does not have a wife is without goodness, without a helper, without joy, without blessing, without atonement.

From a psychological perspective, marriage rounds out men and teaches them to be more empathic and self-aware. Men, being naturally more extroverted due to their aggressive instincts, may lack self-reflection without input from a woman who is more attuned to bonding, empathy, and affection.

According to researchers Monin and Clark (“Why Do Men Benefit More from Marriage Than Do Women? Thinking More Broadly About Interpersonal Processes

That Occur Within and Outside of Marriage”, Joan K. Monin & Margaret S. Clark, Published online: 27 May 2011, Springer Science+Business Media, LLC 2011):

• Although marriage is associated with health benefits for both men and women, research has consistently shown that men derive more benefit than women (Goldman et al. 1995; House et al. 1988; Kaplan and Kronick 2006; Kiecolt- Glaser and Newton 2001). 
• Men typically benefit from the reduction of daily hassles for men due to wives’ provision of more household maintenance (Bolger et al. 1989; Greenstein 1996; Hochschild and Machung 1999; Thompson and Walker 1989).
• Since men and women differ in how much support they give and receive outside of their marriages or romantic relationships. If women have more mutually responsive communal relationships outside of marriage, they may need marriage less than men do in terms of maintaining their health. Multiple lines of research provide evidence for the idea that women benefit more from close relationships outside of their marriages than men do. Research shows that women feel closer to others (Monin et al. 2008), give (Wellman and Wortley 1990) and receive more social support (Turner and Marino 1994), and are more likely to have confidants (Booth 1972) outside of their marriage.
• Additionally, women are more likely to express their emotions outside of their marriages than men are (Monin, Feeney, & Clark, unpublished data). Although marriage is still an important source of support and intimacy for both men and women, men may be relying on this source of support more than women do.
• In another study, men’s wage earnings, increased by 22% if they are married. (Leslie S. Stratton, “Examining the Wage Differential for Married and Cohabiting Men,” Economic Inquiry 40 (April 2002): 199–212.) This is similar to the Gemara’s teaching (Bava Metzi’a 59a): “A person must always be careful about respecting the honor of his wife, as blessing is found in a person’s house only because of his wife.

Considering all these opportunities for relational wholeness and growth that marriage provides, the Hebrew term for "bachelor," meaning "empty one," succinctly expresses this concept.