Whilst I am always interested in learning new words, it is the never so much the meaning as the origins which intrigue me. Overhearing a conversation where one learned there were two meanings for one word made me think about the etymologies, the origins of the word. Were there two completely different origins and the identical spelling is pure coincidence or has the word simply been used to mean two different things?
I took a look at a number of examples and discovered the following:
Address: as a verb to mean 'to guide or direct', it came to English in the 14th century from Old French adrecier meaning 'straighten, set right' and from Latin addirectaire with the same meaning. When it comes to the noun and meaning 'dutiful or courteous approach' it is first seen in the 1530s and is derived from the verb. As a noun the sense of 'formal speech' dates from the 1750s and in referring to a place of residence is not known prior to 1888.
Arm: when referring to the upper limb the word can be traced back to Proto-Germanic armaz and Sanskrit irmah and has probably remained largely unchanged since the development of Proto-Indo-European. Note, however, the later change in languages such as Greek arthron 'a joint', Latin armus 'shoulder', and Armenian armukn 'elbow'. In the sense of 'a weapon' it can be traced to Proto-Indo-European ar 'fit, join' and eventually used as a verb.
Bank:as a financial institution dates from the 15th century and originated in the Italian banca meaning 'table', coming to English through Middle French banque with the same meaning. Whilst unrecorded this almost certainly came from the Germanic for a 'bench'. The second use is for the slope or a bank of earth. This certainly came to English from the Proto-Germanic bangkon meaning 'slope' and having a common origin with bankiz or 'shelf'. Hence the word, despite having two quite diverse uses, has the same source in the early European tongues but by coming to English through very different routes has two quite different meanings.
Bark: when referring to the sound made by a dog, is from Proto-Germanic berkan and simply imitative of the sound. When it comes to the noun describing the covering on the trunk of a tree, the term most likely came to English from Old Norse barkr and from Proto-Germanic barkuz and seem certain to be from the name of the birch tree.
Base: when used as a verb or noun to refer to a low point or foundation, it is surprisingly recent and not seen before the 14th century as a noun and in 1841 as a verb. Both are derived from Old French bas 'depth', Latin basis and Greek basis 'foundation, step'. Also used as an adjective meaning 'lowly', this has exactly the same origins.
Beam: in the modern sense would refer to rays of light and seen since the 15th century. (Smiles and radio transmissions being derived from the same source.) Also used today to refer to wooden beams used for construction purposes, this originally referred to the 'living tree' and ultimately comes from Proto-Indo-European bheue simply meaning 'to grow'.
Board: when referring to 'a plank' it can be traced to Proto-Germanic burdam and ultimately Proto-Indo-European bhrdh both with identical meaning and thus likely one of the earliest words coined. Interestingly there is also a Proto-Indo-European bherdh, almost the same word but used in the sense 'to cut', further evidence of this being among the first key words used by the people of the European continent. The word 'board' has a number of other meanings - including 'to get onto', 'food and lodging' - are both derived from the original 'plank' meaning. In the case of the 'food and lodging' meaning, this comes from the use of a 'board' as a table top, a board not fastened down but simply resting on the trestle below - one side polished and on which the food was served, the reverse scrubbed clean but left in its natural state on which the food was prepared.
Bolt: as a verb used, in a general sense, to mean 'move rapidly' in its various forms is seen from the 13th century and undoubtedly comes from the bolt or arrow used in a crossbow. The stout arrow known as a 'bolt' is ultimately from Proto-Indo-European bheld or 'to knock or strike'.
Bow: when used to refer to the weapon used to fire an arrow comes from a Proto-Germanic bugon with the same meaning. The reference to a looped knot is seen from the middle of the 16th century and speaks of it being shaped like the weapon.
Box: the noun referring to the wooden container is probably from the Greek where pyxis refers to a box made from boxwood', while the Greek for 'the box tree' is pyxos. When it comes to 'box' being used in the sense of 'a blow' the origin is much later and completely unrelated. Traceable only as far as the 13th century, it can be found in the Middle Dutch boke and Middle High German buc, likely imitative of the sound.
Can: as the 1st and 3rd person singular of 'know', the origin of which is Proto-Indo-European gno, has its vowel change through influence from other early European languages such as Old Frisian kanna and Proto-Germanic kunnan.. In the sense of a 'container' the origins are uncertain but came to English from Proto-Germanic kanna and seen in Late Latin canna with the same meaning and early Latin canna 'reed pipe, boat'.
Cast: began as meaning 'to throw' and came from Old Norse kasta, every other usage came from here - including 'group of actors', 'an eye condition', 'turn', 'a shape from molten metal'.
Chip: in the sense 'piece of wood' can be traced to Proto-Indo-European keipo 'sharp post' and eventually came to mean 'small piece of wood' in Dutch kip and smiliar. The later use to mean 'that cut off' has clear connections and first seen in the early 15th century.
Clear: as a verb and as an adjective - be it to tidy, prove innocent, explain and a number of others - seen since the 13th century and new uses can be found up to the end of the 19th century. The many uses indicate several sources from other languages and there are a number of cases of influence from other languages where the meaning is somewhat different: Old French cler 'bright, shining', Latin clarus 'clear, loud', Italian chiaro and Spanish claro 'illustrious, famous, glorious'. All these can be traced to Proto-Indo-European kle meaning 'to shout'.
Club: used as a noun to mean 'a gathering, an association', is first known in a document from the early 17th century. In the late 13th century we first find the use as 'sizable stick used as a weapon', this from the Old Norse klubba meaning 'cudgel'. Note the suit in playing cards is unknown prior to the 17th century, earlier it being known by its Spanish or Italian names of basto and bastone respectively. By the 17th century the shape shown was that of the trefoil, Danish klover and Dutch klaver literally 'a club at cards' but clearly related to the English 'clover'.
Current: is first applied to the flow of electrical force in 1747, this obviously taken from the flow of water and derived from Old French corant meaning 'running, lively, eager, swift' and from Latin currere 'to run', itself from Proto-Indo-European kers 'to run'. It has been used to mean 'the present time' since around 1570 and should be seen as using 'running' in the same sense as when we speak of something currently being shown.