Patnee means wife. And wife who legally can live with a man for his household purpose, to expand his family (by bearing children for her husband), and in the last to be taken to her last rites by her husband.

In our Hindu culture there is a law of one man one wife. She has been given the status of Devee (goddess), she is to be worshipped in the house, she is always respected in the house.

Four Roles of wife
Normally, all over the world, people in couples. Only the powerful and rich people keep more than one wife. Long before Kings used to have wives even in hundreds and thousands. Although Raam's father Dasharath had more than 300 wives, but Raam has always been praised for having only one wife. In fact, all things were one for Him - He used only one arrow (infallible) and spoke only one word (never backed out)

द्विशरं नाभि संधत्ते रामो द्विर्नाभिभाषते ।

सोमस्य जाया प्रथमं गन्धर्वस्तेऽपरः पतिः । तृतीयो अग्निष्टे पतिस्तुरीयस्ते मनुष्यजाः ॥ (अथर्व १४/२/३)

Some usage of words for 4 wives in Vedic literature are indicated here. All the 4 are used in Shatapath Braahman (here Braahman word means explanation, not any caste), chapters 13/4/1 and 13/5/2. Saayan has explained these rituals as per Kaatyaayan Shraut Sootra (20/12) which has given meanings of these wives - Mahishee means first married wife, Vaavaataa means who is kept in house (?), Parivriktaa = kept outside (deserted ?), Paalaagalee  = daughter of messenger (?). Shraut Sootra is the method of rituals. Shaankhyaayan Shraut Sootra also describes it.

चतस्रो जाया उपक्लृप्ता भवन्ति । महिषी वावाता परिवृक्ता पालागली ।
सर्वा निष्किण्योऽलङ्कृताः । मिथुनस्यैव सर्वत्वाय । (शतपथ ब्राह्मण १३/४/१/८)

सायण भाष्य
चतस्रो भार्याः उप समीपे क्लृप्ताः स्थिताः भवन्ति । पालागली दूतदुहिता ।

टिप्पणी -
पत्न्यश्चायंत्यलङ्कृताः निष्किण्यो महिषी वावाता परिवृक्ता पालागलीति । (कात्यायन श्रौत सूत्र २०/१२) -
प्रथम परिणीता पत्नी वावाता वक्लमा, परिवृक्ता अवक्लमा , पालागली दूत पुत्री ।
चतस्रश्च जायाः कुमारी पञ्चमी …..(शतपथ ब्राह्मण १३/५/२/१-८)

Atharv Ved (20/128/10-11) is appendix (Khila) called Kuntaap Sookt. Kuntaap is translated as gambler -Taap = heat or repenting like "Pashchaataap ". But it should mean uncertainties in world due to which there cannot be a strict rule. Each rule has some exceptions to suite the society. Here too, Vaavaataa means beyond the bounds of Father-in-law (Shwasur), i.e. family. Parivriktaa means the opposite of under control of family. These indicate two aspects of wife - one is within the house and the other outside. Husband will have corresponding relations. Both ways, wife improves the family. Totaa word is written here, not used anywhere else. Meaning of root verb "Tu" is to increase, move, harm.

परिवृक्ता च महिषी स्वस्त्या च युधङ्गमः । अनाशुरश्चायामि तोता कल्पेषु सम्मिता ॥१०॥
वावाता च महिषी स्वस्त्या च युधङ्गमः । श्वाशुरश्चायामि तोता कल्पेषु सम्मिता ॥११॥ (अथर्व २०/१२८)

Some other usage of these words in Vaidik texts are given below -

प्रास्मै गायत्रमर्चत वावातुर्यः पुरन्दरः । याभिः काण्वस्योप बर्हिरासदं यासद् वज्री भिनत् पुरः ॥ (ऋक् ८/१/८)
आ त्वाद्यः सधस्तुतिं वावातुः सख्युरा गहि । उपस्तुतिर्मघोनांप्रत्वावत्वधातेवश्मिसुष्टुतिम् ॥ (ऋक् ८/१/१६)
या वा अपुत्रा पत्नी सा परिवृत्ती (परिवृक्ती)- (शतपथ ब्राह्मण ५/३/१/१३)
सुवरीति परिवृक्ती । (तैत्तिरीय ब्राह्मण ३/९/४/५)
प्रहेयो वै पालागलो (दूतः) व्वानं वै प्रहित एति । (शतपथ ब्राह्मण ५/३/१/१)
यैव प्रथमा वित्ता (भार्य्या) सा महिषी । (शतपथ ब्राह्मण ६/५/३/१)
महिषी धाय्या । (कौषीतकि ब्राह्मण १५/४) भुव इति वावाता (पत्नी) । (तैत्तिरीय ब्राह्मण ३/९/४/५)
तष्टासि तृष्टिका विषा विषातक्यसि । परिवृक्ता यथा सस्यृषभस्य वशेव ॥ (अथर्व ७/११३/२)
परिवक्ते पति विद्यमानट् (ऋक् १०/१०२/११) सं ते वावाता जरतामियं गीः (ऋक्  ४/४/८)

Analysis of these indicate that, role of wife has been divided into 4 aspects-like 4 Varn (grades of persons) or 4 Aashram (stages of human life). These aspects of wife has the meanings- Mahishee = controller of house (mistress). Vaavaataa = role in the house, Parivriktaa = role outside house, Paalaagalee = link in the family. In this sense, wife is called Vadhoo = which binds the family.

Neeti Saar writes the following six qualities of a good wife--
Kaaryesh Daasee, Karaneshu Mantree, Roopesh Lakshmee; Kshamaya Dharitree
Bhojyeshu Maataa, Shayaneshu Rambhaa, Shat Dharm Yukt Kul Dharm Patnee.
(means Kaareyshu Daasee (in duties like a servant), Karaneshu Mantree able like a good minister), roopeshu Lakshmee (looks like a Lakshmee), Kshamaya Dharitree (in patience like our mother earth),

Bhojyeshu Maataa (feeds like mother), Shayaneshu Rambhaa (in bed like a prostitute) Shat Dharm Kuladharm Patnee (such a woman who has these six qualities is a real wife)
Works like a servant, Advises like a minister, Feeds like a mother, makes love like a nymph, is as beautiful as Lakshmi, and forgiving like the earth - these are the six Dharm of a wife.
[Some say it is from Bhrtrihari, or Rukmini Kalyaanam]

Kaaryeshu Mantree; Karaneshu Daasee; | Bhojyeshu Maataa; Shayaneshu Rambhaa
Dharmaanukoolaa Kshamayaa Dharitree; Shad gunya Metaddhi Pativrataanaam
Garud Puraan, Poorv Khand, Aachaar Kaand, 64/6

Kaaryeshu Daasee Karaneshu Mantree | Roopeshu Lakshmee Kshamayeshu Dharitree
Bhojyeshu Maataa shayaneshu Rambhaa | Shat Dharmyukta Kul Dharm Patnee (Satkarmaa Naaree Kul Dharmaa Patnee)
[Neeti Saar]
Meaning of the Subhaashhit:
Servant in tasks, minister in execution, Goddess Lakshmee in beauty, Mother Earth in forgiveness, mother in feeding, Rambhaa in bed - union of (these) six actions is a dutiful wife.
Commentary:
At first sight, this seems like a chauvinistic verse. But when one sees the meaning in depth, it really upholds the role of a wife to the highest order.
--The wife serves as if a servant for the whole household. From cooking to cleaning, dusting to moping, she doesn't have any reservations.
--She is very able and clever, like a minister.
--She prudently executes the tasks of the family and organizes the house skillfully. She puts the available resources to good use and doesn't indulge wastefully in unwanted luxuries.
--She is personification of Goddess Lakshmee herself in her beauty. Not because of the beautifying aids she uses, but because of her inner strength, her integrity and chastity give that inner glow and command.
--In forgiveness, she is like Mother earth. Mother earth is used as a simile for forgiveness because she bears the weight and brunt of all the good and bad on her. Likewise, a wife forgives, protects and also corrects, even the unpleasant aspects of her family.
--In feeding the hungry, she is like a mother, as a mother feeds with all her love to a child, she should also feed her husband like that. She will go hungry but still feed her child.
--She is a nymph (like Rambhaa) in satiating her husband.
These six qualities make up a good wife. This is truly epitomized in this shloka.

Negative Aspects of a Wife
Vivaad sheelam,  Swayam Arth chorineem,  Paranukoolam,  Pati Dosh bhaashineem,  Agresineem Anya griha praveshineem,  Bhaaryam tyaaje,  Putra dasa Prasootikaa

If there is a doubt about the existence of husband, can wife can re-marry?
Mahaabhaarat mentions that even when there is a doubt about the existence of the husband, his wife can remarry.

"Aasthhaasyati punarbhyamee damayantee swayamvaram,
tatra gachchanti raajaano raaj putraasch sarvashaha."
--MBH, Van Parv, 70/24.

My Note
I have heard a rule prevails if there is no knowledge of a person for 10 years, it has to be reported and he will be included in the dead list.

A Student's characteristics should be --

Kaag cheshtaa bako dhyaanam, shwaan nidraa tathaiv cha,
Alpa Haaree, griham tyaagee, vidyaarthee panch lakshanam

Baalikaa Cheshtaa, Picture (film) Dhyaanam, Kumbhkarn Nidraa tathaiv Cha
Chaaya Aahaaree, Ticket Tyaagee (traveling without ticket) (ku) Vidyaarthee Panch Lakshnam
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Pitaa Rakshati Kaumaaree, Bhartaa Rakshati Yauvane
Putro Rakshati Vriddhakyee, Na Stree Swatantryam Arhati
Father protects a woman in her childhood, husband protects her in her youth, the son protects her in her old age, thus a woman is never independent.