The biblical word ketoret קטרת means "smoke, odor of sacrifice, incense." According to Klein, all of the forms of the verb קטר (meaning "to smoke, burn incense, etc.) derive from that noun, and literally mean "to produce ketoret." Most of the words with that root are directly connected to that meaning, such as mikteret מקטרת - "pipe", but other's aren't so clear. Let's take a look.
The only Biblical Hebrew word that may have a different meaning is keturot קטרות, found in Yechezkel 46:22. This word is an adjective describing courtyards. The Mishna (Midot 2:5) says it means "unroofed", and are connected to our root because without a roof, the smoke could escape. However, Radak and others say it means "connected", and this is based on the Aramaic meaning of קטר - "to bind". This meaning is found a few times in the Aramaic section of the Book of Daniel, and is cognate with the Hebrew קשר - "to bind", as found in the word kesher - "connection".
A word related to ketoret, kitor קיטור - originally meant "thick smoke, vapor", and in modern Hebrew was adopted for the word "steam." The Hebrew word for locomotive, katar קטר, is connected to the idea of a steam engine, but actually has a more interesting story. Stahl, in his Arabic dictionary, describes how the founders of modern Hebrew were trying to come up with a word for "train." Ben Yehuda suggested kitor, and David Yellin offered katar. Katar had the advantage of both hinting to the steam of kitor, but more significantly was parallel to the Arabic word for train - qitar. This Arabic word originally meant a caravan of camels, and is related to the Aramaic sense of קטר we saw earlier - "to bind." In the end, however, the suggestion of Yechiel Michel Pines was accepted - rakevet רכבת, and katar came to mean just locomotive (not the entire train).
Another word that is possibly related to the sense of "bound" is koter קוטר - "diameter". Koter entered Hebrew in the Middle Ages and was borrowed from the Arabic qutr of the same meaning. The Arabic Etymology Dictionary has the following entry:
quttr : area; diameter [Sem q-tt-r (tie), Heb qotter, Syr qttar (fasten, tie), JNA qttr]
The Arabic qattara - "drip" is apparently related to the meaning of "smoke, incense" (perhaps in the way the incense was prepared), and in light of this, the scholar Lothar Kopf (as quoted in Stahl) connects the two meanings "incense" and "to bind" as deriving from a common meaning "things that follow one another."
One theory says that the name of the country Qatar is also related:
The name "Qatar" may derive from the same Arabic root as qatura, which means "to exude." The word Qatura traces to the Arabic qatran meaning "tar" or "resin", which relates to the country's rich resources in petroleum and natural gas.
Lastly, and most surprising to me, is the English word "nectar". The Online Etymology Dictionary provides an unrelated etymology:
from Latin nectar, from Greek nektar, name of the drink of the gods, which is said to be a compound of nek- "death" (see necro-) + -tar "overcoming"
However, Klein thinks that the word ultimately has a Semitic origin:
nectar, n., the drink of the gods (Greek mythol.) -- L., fr. Gk. nektar, 'drink of the gods', esp. 'wine', which prob. derives fr. Heb. (yayin) niqtar, 'smoked (wine), perfumed (wine)', Niph'al ( = passive form) of the Sem. base q-t-r, 'to make sacrifices, smoke'; qitter and hiqtir, 'he made sacrifices, smoked', are Pi'el ( = intensive form), resp. Hiph'il ( = causative form) of the same base, whence also qetoreth, 'sweet smoke of sacrifice, incense', Talmudic and Targumic Aram. qitra, '(thick) smoke', Ethiop. qetare, 'incense'. From q-t-r, a collateral form of this base, derive Aram. qatara, 'it exhaled odor', (said esp. of roast meat), 'it smoked' (said of fire), qatar, 'vapor, smoke, aroma', Akkad. qutru, 'smoke', qutrinnu, 'incense offering'
We've seen the concept of perfumed and spiced wine before, when we discussed why ancient wine was always mixed with water. While nectar has a much more mild meaning today - "a sugary fluid secreted by plants" - for the Greeks it might have been much more powerful!