Part of speech identification

  Hello, this is my first post here, I like to know these words
kilometer
centimeter

Are those words noun if they are standing alone ? if it's, what kind of noun it's, proper noun or abstract noun or etc ?

After that, I want to indentify the part of speech of the following sentence by using the stanford parser at http://nlp.stanford.edu:8080/parser/index.jsp
if you input,
convert kilometer to centimeter
it gives convert/VB kilometer/NN to/TO centimeter/VB

if you input,
convert 2 kilometers to centimeter
it gives convert/VB 2/CD kilometers/NNS to/TO centimeter/NN

You can refer to the tagset below, my question is, is the first input grammatically correct ? if it's correct the part of speech given by the program seems to be incorrect because
the centimeter should be noun instead of Verb, or am I wrong ? If you add the "2" as the second input the program gives the correct part of speech tagging,
is it because my first input grammar is incorrect ? Thank you.

Reference
1. CC  Coordinating conjunction  25.TO  to
2. CD  Cardinal number           26.UH  Interjection
3. DT  Determiner                27.VB  Verb, base form
4. EX  Existential there       28.VBD Verb, past tense
5. FW  Foreign word              29.VBG Verb, gerund/present participle
6. IN  Preposition/subord.       30.VBN Verb, past participle
218z     conjunction
7. JJ  Adjective                 31.VBP Verb, non-3rd ps. sing. present
8. JJR Adjective, comparative    32.VBZ Verb, 3rd ps. sing. present
9. JJS Adjective, superlative    33.WDT wh-determiner
10.LS  List item marker          34.WP  wh-pronoun
11.MD  Modal                     35.WP  Possessive wh-pronoun
12.NN  Noun, singular or mass    36.WRB wh-adverb
13.NNS Noun, plural              37. #  Pound sign
14.NNP Proper noun, singular     38. $  Dollar sign
15.NNPS Proper noun, plural      39. .  Sentence-final punctuation
16.PDT Predeterminer             40. ,  Comma
17.POS Possessive ending         41. :  Colon, semi-colon
18.PRP Personal pronoun          42. (  Left bracket character
19.PP  Possessive pronoun        43. )  Right bracket character
20.RB  Adverb                    44. "  Straight double quote
21.RBR Adverb, comparative       45. `  Left open single quote
22.RBS Adverb, superlative       46. "  Left open double quote
23.RP  Particle                  47. '  Right close single quote
24.SYM Symbol              48. "  Right close double quote

Convert X kilometers to centimeters.

Try parsing that with any number for X.

CJ

convert kilometer to centimeter is not grammatical correct sentence ?

Correct.  It's Convert kilometers to centimeters.

the tools is not very accurate

Correct.  It's probably not much more than a dictionary look-up program.  A dictionary would give you just as much information, if not more.

CJ