ਗੁਰਬਾਣੀ ਵਿੱਚ 'ਘਰੁ' ਦਾ ਮਤਲਬ । What does "Ghar" mean in Gurbani?

The word "Ghar" is written in the title (Sirlekh) of Shabads (sacred hymns) written in Sri Guru Granth Sahib Ji. "Ghar" literally means "house". In the context of Gurbani "Ghar" means "the rules of the house" (i.e. rule of reading or singing the particular Shabad).

To understand the "Ghar", the rules of the house, i.e the rules relating to singing or reading the Shabad, numbers have been given. For example 1, 2, 3 etc. 

The below line is "Ghar 1", which means it can be read straight without any break/comma:
ਕਰਿ ਬੰਦੇ ਤੂ ਬੰਦਗੀ ਜਿਚਰੁ ਘਟ ਮਹਿ ਸਾਹੁ॥
kar band-e too bandgee jichar ghat meh saahu. (Ang 724)

The below line is in "Ghar 2", which means the line needs to be read in two parts:
ਹਮ ਭੀਖਕ ਭੇਖਾਰੀ ਤੇਰੇ;  ਤੂ ਨਿਜਪਤਿ ਹੈ ਦਾਤਾ॥
ham bheekhak bhekhaaree tere;  too nij-pat hai daataa. (Ang 666)

The below line is in "Ghar 3", which means the line needs to be read in three parts:
ਜਹ ਹਰਿ ਸਿਮਰਨੁ ਭਇਆ;  ਤਹ ਉਪਾਧਿ ਗਤੁ ਕੀਨੀ;  ਵਡਭਾਗੀ ਹਰਿ ਜਪਨਾ॥
jeh har simran bheyaa;  teh upaad gat keenee;  vad-bhaagee har japnaa. (Ang 670)

The below line is in "Ghar 4", which means the line needs to be read in four parts:
ਊਚਨ ਊਚਾ;  ਬੀਚੁਨ ਖੀਚਾ;  ਹਉ ਤੇਰਾ;  ਤੂੰ ਮੋਰਾ॥
oochan oocha;  beechan kheechaa;  hau teraa;  too meraa. (Ang 821)

In reference to the above rule, there can only be a maximum of 8 Ghars one particular line.

However, "Ghar" can also means the total number of words in one verse of a Shabad. Read more about this on: https://www.theworldsikhnews.com/guru-granth-sahib-ghar/

Source: "Ghar Da Vidhaan" book, authored by Dr Charan Kamal Singh