Gaelic-English
dictionaries & meanings in Gaelic
An Stòr-dàta Briathrachais
Gàidhlig: The Gaelic terminology database (1993)
The School Gaelic Dictionary
(Am Briathrachan Beag) by Patrick MacFarlane (1912)
Gaelic vocabulary for parents
dictionary
of political terms (Faclair na Pàrlamaid), Scottish government
resources: thematic dictionaries
The illustrated Gaelic
dictionary, specially designed for beginners and for use in schools, including every Gaelic word in all the other
Gaelic dictionaries and printed books, by Edward Dwelly (1918)
Gaelic-English dictionary
by Ewan MacEachen (1922)
The school Gaelic dictionary
(Am Briathrachan Beag) by Patrick MacFarlane (1912) or online
version
Etymological dictionary
of the Gaelic language by Alexander MacBain (1911) or online version
(shorter)
Dictionary of the
Gaelic language by Norman MacLeod & Daniel Dewar (1909)
Pronouncing
Gaelic dictionary by Neil MacAlpine (1866)
Vocabulary English and Gaelic by Patrick
MacFarlane (1815)
Dictionarium scoto-celticum:
Gaelic-English-Latin dictionary, published by The Highland Society of Scotland (1814)
Guide to Gaelic conversation and pronunciation
& vocabularies, dialogues, phrases, and letter forms, by Lachlan MacBean (1905) or online
version
Gaelic vocabulary
and phrase book by James Munro (end 19th)
The tourists hand-book
of Gaelic and English phrases for the Highlands, by Mary Mackeller (1880) or online
version
Gaelic proverbs and proverbial
sayings, with English translations by Thomas MacDonald (1926)
Our Gaelic proverbs,
a mirror of the past, by Angus MacGillivray (1928)
A collection of Gaelic
proverbs and familiar phrases based on MacIntosh's collection, by Alexander Nicolson (1882)
A collection of Gaelic
proverbs, and familiar phrases with an English translation, by Donald MacIntosh (1785)
Scottish land-names,
their origin and meaning, by Herbert Maxwell (1894)
The
Gaelic topography of Scotland by James Robertson (1869)
Gaelic names of beasts
(Mammalia), birds, fishes, insects, reptiles, etc... by Alexander Robert Forbes (1905)
Gaelic names of plants
(Scottish and Irish) with notes on their etymology, their uses, plant superstitions... by John Cameron (1883)

Gaelic course & Gaelic-English vocabulary
pronunciation (with sound)
basic grammar of Gaelic language
pronunciation (phonetic)
Gaelic course (bbc):
basic vocabulary (with sound)
Gaelic grammar, principles
of phonology and etymology & proper and place names, by George Calder (1923)
Gaelic self-taught
by James MacLaren (1923)
Elementary course of Gaelic by Duncan Reid & Norman
MacLeod (1913)
How to learn Gaelic,
orthographical instructions, grammar, and reading lessons, by Alexander Macbain & John Whyte (1906)
Elements
of Gaelic grammar by Cameron Gillies, based on the work of Alexander Stewart (1896)
Elements of Gaelic
grammar by Alexander Stewart (1886)
Practical
grammar of the Scottish Gaelic by James Munro (1843)
books about Scottish Gaelic language: Google
books & Internet
archive
resources about Gaelic language
The Scotsman: in Gaelic or in English
(newspaper)
An Gàidheal Ùr [PDF] monthly
Radio nan Gàidheal (BBC) > listen
The Gaelic reader
with notes and vocabulary, by Malcolm MacLennan (1913) 
Gaelic poems by Alexander
Cook (1882)
Carmina Gadelica (Gaelic
songs): hymns, songs, collected by Alexander Carmichael, in Gaelic & translation in English
Popular tales
of the West Highlands collected by John Francis Campbell (1860) in Gaelic & translation in English: I & II
- III - IV
Tiomnadh Nuadh: New Testament in Gaelic
(1813)
Gospel of Mark in Gaelic, multilingual text
Tha gach uile dhuine air a bhreth saor agus co-ionnan ann an urram 's ann an còirichean.
Tha iad air am breth le reusan is le cogais agus mar sin bu chòir dhaibh a bhith beò nam measg fhein ann an spiorad bràthaireil.
Scotland: maps, symbols, heritage & documents
Irish Gaelic language & Manx Gaelic language
Celtic languages (in French)
Scots language: language of the Lowlands