There are several Icelandic words for “head”, i.e. the thing sitting on your shoulders. Which word you use depends on what you are doing with your head at that particular time. Here are a few examples you may encounter 🙂

að hrista höfuðið – to shake your head, especially in a side to side motion, indicating “no”.

að hrista – to shake
present past
ég hristi hristi
þú hristir hristir
það hristir hristi
við hristum hristum
þið hristið hristuð
þau hrista hristu
höfuð (n) – head
singular plural
nom höfuð höfuð
acc höfuð höfuð
dat höfði höfðum
gen höfuðs höfða

Hann spurði hana hvort hún vildi fara, en hún hristi höfuðið.
He asked her if she wanted to go, but she shook her head.

að kinka kolli – to nod your head, indicating assent, saying “yes”.

að kinka – to nod
present past
ég kinka kinkaði
þú kinkar kinkaðir
það kinkar kinkaði
við kinkum kinkuðum
þið kinkið kinkuðuð
þau kinka kinkuðu
kollur (m) – head
singular plural
nom kollur kollar
acc koll kolla
dat kolli kollum
gen kolls kolla

The verb kinka takes the dative case:

“Er allt í lagi?” Hann svaraði ekki, en kinkaði kolli.
“Is everything all right?” He didn’t answer, but nodded his head.

Other than the general meaning of head, kollur can more specifically refer to the top or crown of the head.

Another word for head is haus. I think it’s used more when talking about animals’ heads, but there are many expressions that use it. Most relevant to this post would be

að hengja haus – to hang your head (in shame, presumably)

að hengja – to hang
present past
ég hengi hengdi
þú hengir hengdir
það hengir hengdi
við hengjum hengdum
þið hengið hengduð
þau hengja hengdu
haus (m) – head
singular plural
nom haus hausar
acc haus hausa
dat haus hausum
gen hauss hausa

Engin ástæða að hengja haus. – No reason to hang your head.

Another “head” word is one I just recently came upon, as part of the police blotter. It was reported that someone headbutted a taxi driver. If you should ever need to report something similar to the police, the correct verb would be skalla 🙂

Maðurinn skallaði leigubílstjórann. – The man headbutted the taxi driver.

að skalla – to headbutt
present past
ég skalla skallaði
þú skallar skallaðir
það skallar skallaði
við sköllum skölluðum
þið skallið skölluðuð
þau skalla skölluðu
skalli (m) – head (crown)
singular plural
nom skalli skallar
acc skalla skalla
dat skalla sköllum
gen skalla skalla

The related noun is skalli, which can refer to the crown of your head, as well as being the word for baldness.

Hope this helps you recognize a few of the more common phrases involving the words for “head” 🙂