VATICAN CITY (CNA/EWTN News) - Numerous bishops voiced alarm over the lack of a clear definition of marriage in the synod's controversial guiding text, prompting a call for one based on scripture and Church teaching to be added.

"The Instrumentum Laboris nowhere defines marriage. This is a serious defect," group "D" of the four English-speaking circles wrote in their second report, published Wednesday.

This lack of definition "causes ambiguity throughout the text," the group wrote, suggesting a paragraph from the 1965 Second Vatican Council document "Gaudium et Spes" as a correction.

The Vatican II document states that marriage between a man and a woman has "been established by the Creator and qualified by His laws, and is rooted in the conjugal covenant of irrevocable personal consent."

"By their very nature, the institution of matrimony itself and conjugal love are ordained for the procreation and education of children, and find in them their ultimate crown," the document reads.

"Thus a man and a woman, who by their compact of conjugal love 'are no longer two, but one flesh,' render mutual help and service to each other through an intimate union of their persons and of their actions."

Published Oct. 14, the prelate's observations came in the second round of small group reports released during this year's synod of bishops on the family.

Pope Francis officially opened the 14th Ordinary General Assembly of the Synod of Bishops Sunday, Oct. 4, with the event closing on Oct. 25.

The gathering is divided into three parts, with each week dedicated to one of the three sections of the instrumentum. So far the bishops have spent the first week of the meeting discussing the document's first section, titled "Listening to the challenges of the family."

Discussion has moved onto the second part, titled "Discernment of the family vocation," and will culminate next week with the third, "The mission of the family today."

Divided by language into 13 groups with around 20 members each, small groups are playing a larger role in this year's synod. While the groups' individual reports were only published once last year, they are now being published after each of the synod phases.

One small group is in German, four in English, three in Spanish, two in Italian and three in French. Groups were determined by both the language of participants and the requests of the synod fathers.

Group "D" of the English speaking circles - led by Cardinal Thomas Collins of Toronto and Archbishop Charles Chaput of Philadelphia - said that while the text of the synod's guiding document has "many good insights on marriage," it could be clearer.

The part dedicated to Catholic doctrine on marriage "stretches over too many paragraphs. It needs to be brought together in a more concise, compelling way," they said.

Likewise, English speaking group "B" - led by Cardinal Vincent Nichols of Westminster and Archbishop Martin Diarmuid of Dublin - said that a "renewed and deeper reflection on the theology of marriage should be one of the fruits of the Synod."

They suggested that the reflection begin with the book of Genesis, "which already provides a definition of marriage as a unique union between a man and a woman, so total and intimate that because of it a man must leave his father and mother in order to be united with his wife."

Along with a clear definition marriage, the passage also provides the three basic qualities of marriage as it was from the beginning, they said, naming the characteristics as "monogamy, permanence, and equality of the sexes."

Many of the groups also expressed concern that the notion of marriage indissolubility was cast in a negative light, and suggested re-phrasing the paragraphs so that the concept is seen more positively, rather than "as a burden," as group "D" put it.

English speaking group "C" - headed by Archbishop Eamon Martin of Armagh and Archbishop Benedict Coleridge of Brisbane - echoed the sentiment,   underlining the need to speak about the indissolubility of marriage "as a gift from God rather than a burden."

They said the Church must find a more positive way of speaking about the topic, "so that people can fully appreciate the gift," and stressed that while Church teaching on the issue "has been constant," the way it is articulated has not been.

Group "C" also said there is a need to express "heartfelt appreciation" for couples who are already living their marriage as a genuine vocation, and referred to their witness as "a unique service to the Church and the world."

In the reports great attention was also given to the topic of women, specifically their role in the Church and those who face violence in the home.

The English group "D" said that violence against women "was a key part of the discussion," and suggested that the instrumentum laboris "be more sensitive" to women abused either by their husbands or within their families.

Other topics touched on by the groups were education and prayer within the family, specifically the importance of participating in Sunday Eucharist together. Groups also pointed to the increasing phenomenon of youth who don't marry, either out of fear or a general lack of confidence in marriage.

An increase in references to scripture was also proposed, specifically passages relating to the family such as the books of Tobit, Hosea and Luke Chapters 1-2.